I tend to think of doctors as mechanics. Often when something breaks on my car, the explanation is "it's an old car, that happens eventually." And when they talk about it after fixing it, it's usually "Toyota's a good brand. Take care of it and you'll get another 100k miles from that engine." If I took my car to my mechanic with nothing wrong and asked what I should be doing to make sure the transmission lasts as lon…
If you're healthy (as in, no symptoms) then managing your lifestyle should be your business, not your doctor's, and most advice is obvious anyway (don't eat or drink too much, avoid processed food and all manners of sodas whenever possible, sleep well, exercise).
Regarding lifestyle choices, I also think doctors have seen many people getting sick that seemed to be doing everything right, they're not sure what's best. It's very possible stress is a main contributor to poor health, and just worrying too much about it is bad in itself.