I like this emphasis on the impact of health on productivity:
Biological health is upstream of mental health and mental health is upstream of productivity.
Adding to this, I believe engaging in physical activities and working on improving one’s fitness has tremendous effect on productivity in long term. I play tennis regularly, the fact that I make progress in the court and I improve and become a better amateur player increases my confidence in me. I can later use that boost of confidence in my work and personal life.