Some other things I found out so far...

Pain now means different thing. It's no longer "don't do it". Now it's "do it but carefully". Only if you notice pain gradually increasing while doing things carefully it means stop and reevaluate, think what you can alter to improve situation. For me it was aforementioned barefoot shoes. I tried them after my feet started to hurt increasingly in specific places while walking (for health) pretty much the same amount. Change shoes, change chairs, change side where your monitor sits or how high your desk is, the pillow in you bed.

If something is painful but it wasn't when you were younger it mostly means that you need to keep carefully doing it and pain should be decresing, then you can go further even if it's painful and again do it enough at the same level until the pain to go away. It may take weeks or months but it's worth it because it increases your capabilities, makes easier to retain them and reduces the risk of accidental injury.

Another thing are mucus membranes and other delicate exposed or semi-exposed tissues of your body, they are dryer, thinner, less resistant to abrasion, less springy so more prone to pinching. You need to provide the missing lubrication. I'm super careful so I decided to use cosmetics with least amount of ingredients (while keeping desired physical properties) which are cosmetics for newborns. I'm guessing if something won't hurt an infant it probably won't hurt me. Possibly milder soaps also might be better but I'm not sure.

Your immune system is getting weaker so be vigilant about infections and inflammations, accidental damage to skin and such. Try to maintain high hygiene, especially in areas of any damage. Monitor condition of your teeth. Avoid creating environment on your body that is fertile ground for microbes. For example if you have shoes in which your feet get often wet replace them.

The last thing is diet. If you crave something, eat it. Try different things. New things carefully of course. Two exceptions are sugar and salt. If you are craving something with sugar or salt try version without them or if it's not available just skip it. If it's still something you want to eat without sugar or salt it might contain something your body needs. Eat it for as long as you want to eat it. Salt is a bit tricky because you might need salt. You might try eating salt alone, without a meal. If it's tasty alone, you probably need it and you may eat it till it stops being tasty. Sugar is easy, nobody ever needs sugar for any reason so sugar fueled cravings are never valid signal. If you are craving some specific sweet it might be other ingredients it contains. Try them without sugar if you can. I don't say you need to avoid sugar, just that it's just calories. If you decide you need additional calories and nothing else sugar might be fine. Some occasional multivitamin is probably not a bad idea either. Weight is most easily controlled with intermittent fasting. 24h eating, 24h fasting worked great for me. Aim for 23.5 BMI as it correlates with lowest all cause mortality rate.

I don't have much success with sleep, but I know it's needed. If you have trouble with it you might investigate your caffeine intake.

General advice is to listen more to your body and less to your brain. Go for a walk if you feel stiff or something hurts or if just you haven't moved in a while is a good idea even if your brain thinks you absolutely should be binge watching something at the moment, doom scrolling, gaming or being productive.

Also change things often, repetitive strain injuries of every kind are now as dangerous for you as sudden accidental injuries.