At nearly 50 years old, with 15 self employed years "in the business," I've found the most direct way to counter "the effects" is exercise. This is crazy important. And it needs to be strenuous. A walk in the park is not exercise. Hiking uphill, jogging, or some other strenuous sport for an unrested 30 minute period 3+ times a week is usually enough.

Diet tends to follow exercise (and rarely the other way around). So start down the path physically and your body will soon tell you what it needs nutritionally.

Essentially, your body is a learning machine. If you sit and remain inactive your body will simply accept the norm and tune down the things you are not using. This is were all kinds of things start to go sideways, as weight issues can lead to self confidence issues, et al. Lessons learned...