Title could be enough. But since this question is so simple that it looks a bit absurd or obvious...
I'm not talking crazy here in listing these examples, which I believe are world wide common sense:
Eat at least 3 meals daily: breakfast, lunch and dinner. I'd bet most languages even have those 3 separated words to describe each of those meals. If not, they certainly do have this concept.
Have around 8 hours of sleep, every day, despite recent studies.
Brush and floss - rinse doesn't matter.
Wash your hands (notice bath isn't required daily - not world wide at least).
Question here is: what else is there? Sunscreen, maybe? I'd like to know what is, today, considered consolidated things that every single human being should do daily to maintain good health - including nutrition and even, eventually, exercises. For any age or size, if that wasn't clear.