Having a good health is a matter of things you should consume and those things that you should avoid. Everything in excess is detrimental to our health. Well having a good health is really much like having a cancer, though really different thing. The common factor is, it is multi factorial. It depends on the genes and multiple other things. If we know our history we could avoid those that would lead us to that disease. In short there is no way to be heathy, there is just a way on how to prevent unhealthiness.
Eat a balance diet most specially when you re already 30 years of age and above. Exercise is good and a monitoring or a check up will also help.