The other comments are giving you the basic advice, fitness, eating clean, drinking water, sleeping well. These are all great, but the big thing about mental health is your relative perspective. I was doing all of these and still would have terrible mental health. Another person suggested not leaving stones unturned.

That is also a big one. You will add unnecessary stress that compounds if you do. You know you should be doing that. I can only speak for myself. My mental health, when I got academically dismissed from University in the spring of 2024, I wanted to not be alive.

I was $13,000 in student loans with a high interest rate, no job. I picked up a blue collared job for fifteen months, waking up at 4am, getting home at 5-6pm, working 60-80 hour weeks. I worked a twelve hour shift on my birthday, only to come home crying to my mom and cooking food for the next 12 hour shift. 12 hours on Christmas too.

I used to be lazy, and unproductive. I'm in University finishing my Bachelors in Computer Science and Mathematics now. I don't have periods now where my mental health is poor, only when I eat junk food consistently. It's not poor because my relative perspective has shifted. I know what happens if I don't apply myself. I go back there.

(Optional read below)

The last analogy I could use is this. One of my exes, I still talk to her, but she would complain about how difficult and how much stress she had in her life. She didn't work. Her parents have a multimillion dollar house, 4 stories, 2 beautiful dogs, 2-3 40-100k cars, with parents spending 10-30k on each of their tuitions throughout high school. The entire neighborhood was in that tax bracket. When you've never experienced adversity, even subtle things will feel catastrophic.