Here's mine:
Wear sunscreen/moisturise every day, especially on face, neck, decolletage and hands. It's depressing how suddenly everything wrinkles in 40s/50s
Have a rainy day fund. Save a small proportion of your salary for a nice purchase, holiday or running away
Accept and appreciate how you look now. You'll look back in 10 years and think how young you looked
Travel more while you don't have job/caring responsibilities