
1. Mental stimulation
2. Avoidance of negative effect of working out on perfectly flat surfaces
3. Benefit from coping with uneven surfaces
4. Boost to immune system
5. Protection against injury due to cold weather
6. Psychological benefit that goes with physiological benefit
We agree with these points, and would like to add four more:
7. Sunshine is vital for optimum health, especially in winter
8. Exercising outdoors, especially in harsh weather, builds mental toughness
9. Fresh air is good for you
10. Constantly focusing near, then far, improves eyesight
What do all these points have in common? In general, the human body benefits from challenge. It grows stronger when confronted with obstacles, inconveniences, extremities.
So get out there and exercise, every day!