I have noticed that when taking exercise - going for long walks in the countryside, swimming or playing badminton for example - that usually I would get a very hard erection and urge to masturbate. Whenever I went for a walk, somewhere along the route the urges would become irresistible: I would have to look for a secluded place to strip off and relieve myself.
When swimming, usually I had to get out of the water to masturbate in the toilet. In the communal showers and dressing rooms I could see that I was not the only one who had become turned on. In communal showers and dressing rooms I would play with myself, or with another similarly aroused.
It has been proposed that exercise can help to reduce erectile dysfunction:
Physical Activity to Improve Erectile Function: A Systematic Review of Intervention Studies - PMC (nih.gov)
Exercise and erectile dysfunction (ED) - Harvard Health
I have often wondered whether exercise has any permanent effect on penis/clitoris size. Although the consensus says that any increase is only temporary, the few people I know to be exceptionally well-developed suggest that it might. I would be interested to hear what other readers think on this or any of the other issues raised.