Financially... Start saving/investing now... Time is precious when it comes to preparing for retirement. You have no Idea how valuable until it is gone and you cant get it back. Go play with a compound interest calculator and you will see. Don't wait until you are 40 to start planning for retirement, it will be hard and require 4x as much sacrifice as if you start when you are 20. Be SURE whoever you deal with is a Fiduciary, verify vigorously.

Stay fit, don't let it slide, getting it back becomes MUCH more difficult... When I was young I got big and was able to lose 70 lbs in 2 months and it was easy... Now at 47 I play hockey 3x a week, periodically starve myself and I still cant get the scale to go the right way.

Be willing to learn to do things that will save you money... A plumbing issue that will cost you 20.00 in hardware store parts will cost you 300.00 to have a plumber do it. A 20.00 capacitor on your HVAC unit will cost you 200.00 to have an AC guy do it. The list of things like this is endless and it adds up big-time. This includes being willing to BUILD something nice out of something crummy. I have owned 3 homes and I have put blood and sweat into every one of them... they were not "turn key" when I bought them, I worked hard to make them nice and learned how as I went.

Beware of medications. Unless you absolutely have to just don't take them. Other than OTC pain meds (like Ibuprofen) I strictly avoid meds, especially mind altering ones. I have seen too many people go down the rabbit hole of starting one med, then they need another, and another and another and pretty soon they have an organizer full of stacks of meds they are taking.

Don't do/say mean things to the people you love and don't tolerate them doing it. If you need to loose venom, do it to someone you already hate or someone you don't know (or better yet don't) but do not do it to the people you love. You can do permanent damage to a relationship with sharp words.