• Your body is now “out of warranty”. When it breaks in a significant way, it may never get fully better. Don’t do stupid stuff that will break it in those ways.
• If you haven’t figured out yet that you can’t drink, party, or skip sleep like you did earlier in life, learn it quick. Each of these will have a much larger impact on you.
• If you don’t have your retirement savings on track now, you have a VERY VERY short window to correct that. Its going to be much harder now to put the money aside than it would have earlier in life, but you’re in the prime earning years of your life. I would think you will earn more now in the next 10-12 years or so than you will/would have in any 10-12 years of your life.
• Hopefully you’ve learned by now to be comfortable with yourself in your own skin. This means not doing things/buying things to impress other people. You are who you are. This doesn’t mean stop learning or improving yourself, but nobody is going to be impressed with a 40+ year old driving an amazing car. It doesn’t matter how amazing the car is.
• Support younger people. You didn’t get where you are on your own. You had help, advice, and your mistakes were forgiven by those older than you because of your youth. Now its your turn to do that for the younger people. You grew up seeing heroes around you. You are now the hero in a younger person’s eyes. Hold that duty sacred. Be their hero in how you act.
• Embrace change! No, things aren’t like they used to be. No, they shouldn’t necessarily go back to those things just to make you comfortable. Its not our world anymore, it belongs to the younger generations. Understand your ways could be out-of-date or backwards. Your old ways worked for you in that old world. That old world is gone. Be part of the new. You’ll have to do this two or three more times before you die if you live into your 80s or 90s.
• Stay fit. That doesn’t mean body builder or supermodel. It means be moderately active so that picking something up doesn’t cause a strain injury that will take you 6 months to a year to recover from. You shouldn’t be out of breath walking up stairs. If you are, make changes. You’re likely already seeing the difference in your peers with those that stayed fit vs those that didn’t. Be part of the first group, not the second. If you are in the second group, you can change to the first by taking care of your body and eating properly.
• Make a will. You will die and there is nothing you can do to stop it. Dying without having a will makes some of your assets evaporate in probate and may mean your money/assets go to people you may not want.
• Go to the goddamn doctor for wellness checkups! You’re entering the time of life where conditions found early are treatable. Don’t dying/become disabled because you were too lazy or afraid to go. Yes, some of the things are going to be uncomfortable, but I can tell you its much more comfortable than debilitating pain or death.

You might look at the list above and think it negative for you now. Its not at all. This is the prize for living to this age. You likely have some friend or family that died before 40. You are here to see this part of your life. Make sure you’re still here to see 50, 60, 70, with as much of your body and mind as you can.

Good luck!

Didn’t see anyone suggest it, but I can’t recommend it enough, spend time with your parents, and, if they’re still alive, your grandparents!

This really put it into perspective for me.

If you were a late baby like me, your parents are likely getting into their 70s now. You may have 20 years with them. You may have 5. I’m lucky if get to see mine once a month because of work. That’s around 60-240 times left to see them. If I spend an hour with them each time(which is a stretch), that’s 10 days tops. Enjoy the time you have with them and pray you’re lucky.

Also, if you have any loved ones, tell them you love them every chance you get. My wife and I have traded "I love you"s nearly every day for the past 23 years. You never know when it’ll be the last time, so say it as much as you can to anyone you care about! It doesn’t cost anything, and tell me it’s not great to hear when someone says it to you. Spread that shit around!

Lastly, if you can afford it, travel. You don’t have to travel the whole world, and it doesn’t have to cost a fortune. I know people hate on them, but my wife and I book at least 1 AirBnB a year. We find a cheap place that’s only a day’s drive away and book it for a week. Just get outside of the safety net that is the streets and places you know.

For that matter, take any opportunity you can to make new memories. We are creatures of habit, and our brains don’t like to waste. It’s believed that one of the reasons our days feel like they fly by is because we’re following a routine that our brain meshes with the memory of similar experiences and routines to save energy. Being in new places, experiencing new things, and making new memories may help with breaking up those moments where the day, week, month, or year are gone in a flash.

#1. Don’t get fat.

Most physical things are use it or lose it, so don’t slow down, move around, have sex, dance, lift weights and definitely do yoga but:

The one physical effect I’ve suffered getting older is that it takes for fucking ever to heal or recover. So don’t neglect rest and recovery either. Especially with lifting, every other day may work better now.

Don’t get old too soon, because then if you live a long time, you might be old for decades, wait until you are closer to the end to get old.

Most of all - enjoy! Enjoy life, now you have more experience and can feel it more. Like really look around at all the amazing things in the world. Even now. So much beauty, so much joy.

stretch

Do whatever you can to get away. Even for just 3 day weekends. Even just camping should be inexpensive enough.

If you can afford more … Get as far away as possible. Stop making excuses.

Eat your vegetables and exercise.

If you’re fat, lose weight. It’s a risk factor for practically everything and you’re getting old now whether you like it or not. You can at least stop causing further damage.

Read books. It helps you stay sharp. If you just can’t read, do something else daily that uses your brain.

40 is where your slow decline from your 20s and 30s starts to accelerate.

Be more active, but not so active you risk injury.

Wear sunscreen

Other than that, keep an eye on your health - eat well and move because there’s a reckoning coming and it may only be a decade away (I’ve just been through it with friends and it’s rough). Getting your body in order now is better than trying to fix it later when it’s already going wrong - it’s doable but it gets harder the longer you leave it.

Smoke weed erry day

Stretch every day, holy shit that makes all the difference for mobility. It takes about 5 minutes when you wake up in the morning.

Just off the top of my head:

• If It’s at all possible, retire early! Look into FIRE (Financial Independence, Retire Early)
• Carry as little debt as possible
• Max out your 401k (otherwise you’re leaving money on the table!), build a savings account, and maintain at least 6 months’ expenses worth of cash in an emergency account
• Where you can, plan ahead for large purchases (e.g., vacations, new roof) and make them in cash instead of financing them
• Minimize consumption of goods to maximize financial power (i.e., don’t get sucked into lifestyle creep!)
• Do spend money on things that are high-quality and will last
• Lift heavy things often
• Don’t skip cardio
• Hydrate!
• Use sunblock (physical >>> chemical)
• Get your routine medical stuff (e.g., mammograms start at 40), even the uncomfortable ones (colonoscopy!), and don’t wait until minor things become major to get them checked out
• Be calm, rational, and intentional in your interactions with others, and if you’ve behaved poorly, give a heartfelt apology. This is especially important with your significant other.
• Pay closer attention to your parents’ needs - they are aging and will start to need help they may not be willing to ask for
• Don’t be afraid to remove bullshit from your life. That one “friend” who you never want to hang out with because they just drain your energy? It’s OK to let that friendship go.

I don’t have kids so no advice there.

I felt pretty good at 40. By the time that decade ended I was a wreck physically. I would appreciate your health if you still have it. And use it if you still have it.

Stretch and practice meditation. I started in my 50th year, do it every day, and wish I’d started sooner.
The trick to doing it everyday is to view it as a matter of hygiene instead of exercise. I won’t leave the house when starting the day without first brushing my teeth, stretching and meditating, taking a shower. It’s like rinsing your mind with fresh water.

Lift. Heavy. Things. And Train. Your. VO2 Max. Eat. Fibre.

I’m only 43 so it’s not like I’m far ahead of you, but here’s what I know. You don’t have enough insurance, especially if you have a family; auto home or life. You’re not saving enough for retirement, better bump up those 401k contributions or consider an IRA. Don’t move heavy things anymore, herniated discs are more common and no joke. You aren’t seeing the doctors enough either; get your yearly and don’t skip the dentist, especially if you’re in the US. Dental care once you’re on Medicare is just not reasonable and I’m watching my retired father making some tough decisions on if he should keep his teeth or not.