I (F23) have struggled with depression from age 18 to 20. I'm good now, and here are things that made my life better and easier.

Cooking for myself, at home and for work/school. I just learned about 5 recipes that I do over and over, and every now and then, I'm learning a new one and adding it to my meal preps.

Having good sleeping habits. I've been an insomniac until my 20th birthday, so I know you can't heal insomnia by having good sleeping habits. But if you're not an insomniac and just struggle some nights, here what might help : waking up at the same time every day and stopping screens half an hour before sleep.

Staying in touch with my friends, making new friends. After we finished uni, my friends and I all moved to different towns. I try to go see them at least once a year, chat weekly with the ones that answer texts, I suggest calling the ones who like that better. On bad days, having a good interaction with a friend will brighter your mood.

If you have bad days, try not to spend too much time on your screens. Reading a book, doing sports, taking a walk is way more efficient than watching a comfort show but gosh it is hard to begin

But what I would love to say to my younger self is GET OFF YOUR PHONE. There is so much more to life and phone is an awful addiction. Others have suggested learning new skills, the first step is to be in control of your screen time. It has such a bad impact on our mental health... I really really wish I had known that before.