If we assume mental health is physical health, then the more physical we can get, the better. Photography as a great solution.
How can photography help?
Some ideas:
1. Documenting your physical health
Rotator cuff strength and beyond.
2. Photography gives you a reason to leave your house














The more you go out and wander and do stuff, the better. For example when I go to the park to workout, I bring along my camera and have fun shooting photos along the way, or even during my workout via video, then I take screenshots of my video later as still photos.
3. Photography and physical fitness
To me, still photos and moving photos (video) are all photography.
A new frontier — nobody has yer cross pollinated fitness and photography in a meaningful way (yet). Let us consider — as a photographer, you need to be very physical. Strong legs (thunder thighs) are good.
The most important muscle for a photographer is his or her legs.
4. The buffer I am, the more socially confident I am.

My theory:
Working out increases your testosterone, which augments your courage and self esteem.
Testosterone is good
This interesting study via Nature on testosterone. From the study abstract:
Endogenous testosterone promotes behaviours intended to enhance social dominance. However, recent research suggests that testosterone enhances strategic social behaviour rather than dominance seeking behaviour.
The result:
The results showed that, among the most senior participants, higher testosterone was associated
with lower acquiescence. Conversely, higher testosterone among the lower-status participants was associated with higher acquiescence. Our results suggest that testosterone may enhance socially dominant behaviour among high-status persons, but strategic submission to seniority among lower- status persons.
This means as a photographer on the streets, you are not going to acquiesce (not allow yourself to get bullied) if you have higher testosterone in street photography.