Don't stay up late. People born after 90 who know how to keep fit generally don't stay up late, because they will understand that staying up late is not good for their health and is very harmful.
Pay attention to exercise. After 90, they usually pay attention to exercise and make themselves healthier. They usually like running or going to the gym to exercise.
After 04 90, people generally don't overeat. After 90, even if you especially love to eat, you will not overeat. They follow the principle of eating well and eating healthily.
Pay attention to relax yourself after 05-90. Things done after 90 are generally relatively calm. No matter what happens, they can handle it properly.