Not someone with any medical expertise, but here is some stuff I kind of think

-Don't get fat. Stay at a healthy weight forever

-Eat a balanced diet, 3 meals a day

-Walk daily

-Get up from desk and move every so often

-Sleep enough

-Don't overwork

-Go to the dentist every 6 months and do what they say

--Don't skip the dentist because you don't have insurance or something. Cleanings every 6 months are necessary for keeping your gums healthy, even if you brush and floss

-Do some strength exercises a few days a week (calisthenics or weights)

--Always prioritize not injuring your joints or back over gains

--Go to a doctor and PT if you injure yourself, don't start doing random foam roller stuff from the internet