When I was younger, in yeshiva, one Friday after class I was going to play ball, wearing shorts and a t-shirt. While walking up the block, I saw the wife of a big Rav in the community walking with her kids who she’d just picked up from school. She stopped me, and said to me, “I assume you’re going to play ball now?” I replied in the affirmative. She said, “My husband would be so happy if he saw you! He laments that some guys seem to think it’s bittul Torah to go play ball. Exercise is extremely important, and all bachurim should be doing it!”
A few weeks after that, the yeshiva made a rule that you can’t wear shorts while playing ball. Apparently the menahel felt a frum boy shouldn’t wear shorts. A Rebbe who used to play basketball with us sometimes spoke to the menahel about it. The rule was rescinded.