Extending Your Health Span
We only take actions that make sense to us, based on our values, and what we believe about the world. If we believe that becoming obese, and losing mobility and putting up with pain is "normal aging" we're in trouble before we start.
What you Eat Matters
What you eat profoundly affects your long-term health. Your body will adapt to whatever diet you choose to feed it, but not without long term adverse results, if you choose your diet badly.
Sadly, there is strong commercial and political pressure to sell you FOOD of various kinds.
Much of the well-known information about food, even "official recommendations" are propaganda, and not science based.
Take an interest in food, and slowly you will learn how food is used in the body.
If your health is good on a mixed diet, that's an easy diet to follow. If you keep sugar to a minimum and carbohydrates quite low, that should serve your well for a lifetime. However, historically people have not had the control over food that most modern people have. The body doesn't expect to get the same diet, year after year for 70+ years. Until recently, that wasn't even possible, and it might not be good for us.
If the mixed diet, a little bit of everything, is starting to give you problems, there are other choices. Over time, whatever is the "best diet" for you will probably change.
Your Work and Activity
We were made to be active and working and thriving. You need a "work" to do. Preferably a task you love to do. You might also need the sort of work that earns you a living. If so expect to get paid.
Voluntary work, keeps you involved with others, and upgrades your skills. So long as you love to do it, being a volunteer is a healthy thing to do.
Your Family and Friends
We all need the company of other people. Other people give us good models to live up to, and ways to keep our social and intellectual skills alive.
Other people give us feedback on how we are progressing ourselves.
Your Capacity to Learn
Abandon trying to be healthy one disease at a time. Most of us have, or are developing "lifestyle" causes, for the diseases we have. metabolic syndrome, Alzheimer's, heart disease and rheumatoid arthritis, are all examples.
The solution is to keep your whole body healthy, not just parts of it. New information provides the building blocks for fresh concepts and different behaviours. However, trust in the new information has to be built. Do small low risk experiments with your new things you are learning.