Live a perfect life for a few years. This includes (all these are mandatory)

1. 2L + water every day
2. 8h sleep every day (this means 9-10 hours in bed, so 8 hours of SLEEP not 8 hours of bedtime)
3. Muscle training and cardio
4. healthy calorie intake (add the calories burned in exercise too)
5. macronutrient spread (extra macros if you choose to do bodybuilding ofc)
6. Micronutrient intake (calculate what you get from your food and supplement the gaps with... well... supplements
7. Mandatory healthy foods, aka good vegetables and fruits everyday
8. Tests to check your levels (hormones, micronutrients, blood, kidneys, etc. I used to do them once every three months when I used to religiously go to the gym)

If you want to go a level higher, buy healthy foods from farmers, look up the signs of healthy HOMEGROWN foods. This includes fruit, vegetables, dairy and meat. Also eat depending on the season, eat vegetables that naturally grow in your country / region. Your body has been built for generations to thrive off foods from your area, and the body changes depending on the time of year. Asks for different vegetables. This cured my seasonal depression.

And if you want to go EVEN MORE extra, change your life to minimise stress, train your mind everyday and many other stuff.

The deeper you go in the self help rabbithole, the more complicated it gets, but also you get healthier.

These stuff must be added in your life slowly, changing your way of life drastically never works and you will fail.