This article of mine is now two years old, but it is still a great read, if I do say so myself.
Long-term health and the prevention of premature mortality is all about risk factor management. Since you cannot change your age or gender (okay, technically you can, but that’s not really the point, is it?), you must manage the risk factors that are modifiable. These are maintaining a healthy blood sugar, blood lipids, blood pressure, and body weight, which are all possible only if you eat a diet of reasonable quality, exercise regularly (notice I did not say be “physically active”), and don’t smoke. How much of a difference in death risk does this make? A lot.