40 Life Lessons I Know at 40 (That I Wish I Knew at 20)
Practical lessons on career, health, and relationships that you can take action on now
Dear subscribers,
Today, I want to share 40 life lessons after 40 years around the sun.
I recently turned 40 and spent 10+ hours writing down what I’ve learned for my daughters (and you, my dear reader).
Instead of vague pleasantries, I focused on career, health, and relationship lessons you can take action on right now. Let’s dive in.
Career
To have a fulfilling career:
Follow your curiosity, push yourself to do hard things, and learn from failures.
Follow your curiosity
Find the torture that you’re comfortable with. Success in any career requires pain and sacrifice. So try different paths to find what Jerry Seinfeld calls: “a painful thing that you can do for hours that would make others tap out in minutes.” For example, I love torturing myself to write at 6 AM.
Look for the intersection. Find work that satisfies what you want, what you’re good at, and what the market wants. If you're in a job that you're good at BUT drains your energy, please keep looking. It's arguably the most dangerous place to be. For example, I spent three years in management consulting instead of pursuing what I wanted.
Stop waiting for permission. Don’t think: "If only I could get into this great school/company/job, then I could do great work." You don’t need anyone’s permission to do great work! Instead, build something your target customers want and bypass the gatekeepers.
Maximize your luck surface area. Go where your target customers and people who share your dreams hang out. I moved to the Bay Area over 10+ years ago to work in tech. But these days, you can just as easily find your people online. Over the years, I’ve met many great product leaders and creators by consistently posting my thoughts (and memes) on X.
Don’t be the best, be the only. It’s easier to be in the top 10% for a particular set of skills than for a single skill. I can’t claim to be the best PM out there, but I’m probably one of the best PMs building for creators who are creators themselves. Find your unique skill stack that gives you energy and meets market demand.
Push yourself to do hard things
Set audacious goals. Never write off a goal because you think it’s not achievable. Instead, push yourself to tackle tough challenges and build confidence over time. My friend Nat Eliason pushed himself to run marathons, which gave him the confidence to learn coding and even publish a book.
Just ****ing start. The best way to learn if something will work is to try it. Don’t waste time making grand plans or thinking, “Someday, I’ll do this.” Instead, just ****ing start and get real feedback. Go through the understand, identify, and execute loop as quickly as possible.
Put in the reps. As a rule of thumb, I like to put in at least 100 reps before even thinking about quitting. If you’re struggling to stay motivated, hack your brain to track progress by how often you show up instead of by immediate results. I try to focus on uploading podcast episodes weekly instead of obsessing over views.
Learn from failures
Find the right environment to learn. I’ve been at companies where every failure felt like walking on eggshells and others where taking risks and owning up to mistakes was rewarded. Choosing where to work is one of the most important decisions for your career, so find a company that shares your values and lets you grow and learn from your mistakes.
Ask, “What did I fail at today?” You've become too comfortable if the answer is “nothing” for days. With my kids, I believe the sooner they get used to failure, the better off they’ll be. I’ve failed at jobs, relationships, and more — they were some of my lowest moments but also where I grew the most.
Pain + reflection = progress. Failure is only useful if you learn from it. Keep a written log of your setbacks and why you failed, no matter how much it stings. Everyone has at least one big weakness holding them back; your log will help you spot it. Many of my failures came from being too impatient (I am still working on this!).
More reflections on career
Personal finance matters. Nobody taught us this in school, but habits like living within your means, avoiding high-interest debt, and maxing out your 401k match will fast-track your financial independence. Wealth lets you pursue what you want instead of stressing about bills. A great example is Schwarzenegger - he built a real estate business first to be able to try acting without taking crappy roles.
Seek a calendar that you control. Some careers offer money and prestige but zero control over your time. I prefer work that rewards results over face time so that I have the option and time to explore diverse interests. Having an open calendar to choose your meetings is the ultimate flex.
Success isn’t just your career. Don't tie your self-worth to a fancy title or company name. Stacking credentials is a soulless pursuit. Every year, I rank what matters most in my life—this year's stack: health, family, career, friends, and hobbies. Life's dynamic - your interests and priorities will shift over time, and that’s perfectly okay!
Health
When I was young, I thought I had all the time in the world to get healthy. I wanted to "live my youth" by partying (or, let's be real, playing video games) late into the night. But looking back:
I should’ve developed healthy “old person” habits earlier.
It’s great to “live your youth” occasionally, but good health unlocks everything else. To stay healthy, I focus on sleep, diet, and exercise — in that order.
Sleep
Without sleep, you’ll be too tired to eat well and exercise. To get good sleep:
Go to bed and wake up early. I go to bed at 10 pm and wake up at 6 am. Getting up early sucks at first, but having a golden hour for deep work without distractions quickly becomes empowering.
Follow the 3-2-1 rule. No food 3 hours before bed, no water 2 hours before, and no screens 1 hour before. The last one is crucial — having your phone in the bedroom will wreck your sleep (I'm still guilty of doing this too often).
Use simple sleep aids. I wear a sleep mask to trick my brain into shutting down, use mouth tape to prevent snoring (yes, it's a thing), and catch some sunlight in the morning to train my circadian rhythms.
Diet
Losing weight is 90% diet and 10% exercise. I didn’t figure this out until my 30s. I still can’t resist a good noodle soup, but I’ve managed to avoid the “dad bod” by watching what I eat.
Eat more protein. Aim for 0.7-1.0 grams of protein per pound of body weight. This is surprisingly hard for me to do (I don’t like feeling too full), but I try to get my protein from healthy sources like yogurt, salmon, chicken, steak, and protein powder.
Read the labels. It's shocking how often a "healthy" item like yogurt can have 20-30g of added sugar. Always read the labels to avoid buying something bad for you. Don’t buy junk food and leave it around your house—it’s very hard to eat healthy that way.
Treat sugary drinks and alcohol as poison. It's much easier to pack on pounds by drinking calories than eating them. Avoid this stuff as much as possible - I quit alcohol for a year before bringing it back for special occasions only.
Exercise
Work out more for your mind than your looks. Starting each morning with a solid workout is a win I can carry through the rest of my day.
Lift weights at least 3-4x a week. Your muscles naturally start to decline after 40, so build them early and keep working to maintain them.
Find hacks to save time when working out. With two kids, I no longer have time to drive to the gym. So, I bought a Tonal to strength train at home. A simple squat rack or some dumbbells will do as well.
More reflections on health
Use sunscreen every day, rain or shine. It's a cheap way to prevent wrinkles and skin problems. I wish I started this habit earlier.
Get annual check-ups and know your family history. My family has a history of breast cancer, so I got genetic testing for the BRCA gene. Early detection and regular checkups can be lifesavers.
Stress less, live more. Chronic stress wrecks your health. When stressed, I walk outside or do a quick meditation (NDSR) session to calm down.
Relationships
I believe that:
Great relationships are greatest source of happiness in life.
But thinking, "If I can just find my soulmate, then I'll be happy," is toxic. The irony is that relying on others for happiness isn’t the best way to build great relationships. Instead, chase your curiosity and surround yourself with people you respect. You'll naturally attract the right people that way.
Let’s talk about improving relationships with your spouse, family, and friends:
Spouse
Avoid rollercoaster relationships. High-drama relationships might feel exciting in the short term, but they wreak havoc on everything else long-term. I learned this the hard way in my 20s, so don’t make my mistake.
Get comfortable with being alone. Now that I have a family, I've realized that alone time is precious. Don't be needy by seeking constant attention from your spouse. We all need time to ourselves.
Don’t keep score. Relationships are never 50/50; trying to achieve this will only build resentment. Instead, go out of your way to make your spouse happy and communicate openly. The right person will reciprocate.
Family
Call your parents often. Watching my parents age has been humbling, and I now understand how much they sacrificed for me after becoming a parent myself. I regret not calling them much in my 20s and early 30s. Now, I chat with them almost daily, even if it's just for a few minutes.
Live close to your parents after having kids. Having your parents around to help with childcare is the ultimate parenting hack. As they age, being able to see them anytime on the weekend is also precious. I'm just a short flight from my parents, but I wish we'd planned to live in the same city.
Spend quality time with your children. When my kids drive me crazy, I try to remember I only get 18 summers with them before they go to college. Cherish your time together and give them your full attention. Raise them with your spouse, and remember it's never 50/50.
Friends
Keep in touch with a core group of friends. Having a tight-knit group of friends who know you is a great source of happiness. I stay connected with my high school and college buddies over DM. Recently, I took a trip with my high school friend, and seeing him again after all these years with our kids was amazing.
Build a network of weak ties. While deep friendships are crucial, don't underestimate the power of a broad network. I've met many internet friends in real life who share my interests. Being able to share learnings and help each other has been incredible.
Be genuinely curious about others. Everyone has a fascinating story to tell and something to teach you. Being truly interested in others is the best way to build relationships and make new friends as an adult (other than going to kids’ birthday parties!).
More reflections on relationships
Invest in shared experiences. Spend money on epic trips with your family and friends instead of buying stuff. Memories outlast possessions.
Let go of grudges and regrets. Holding onto anger and past regrets will only haunt you. Write down the lessons from your past, but focus on your future.
Avoid the comparison trap. Whenever I feel jealous of someone, I think: "Would I swap my entire life with them, including my family and my kids?" If not, don't envy their fancy LinkedIn title or social media highlight reel.
Remember, these aren't hard and fast rules, but lessons I've learned through experience. Which brings me to the final lesson:
Write down your life lessons and principles.
Writing down your values makes making decisions much easier. Let me know in the comments if these lessons resonated with you and if you have any lessons to share!
Bonus: If you’re wondering about life after 40, I got 600+ replies to my question below:
im gland i found this blog in my 20s, thanks a lot made me realise lot of things
That's a great piece of advices. I'm at my 20's and also some of the things you mentioned is already affecting me. So this advice is more valuable for me. Thanks for sharing. :)