Do you drink a glass of water before or after exercising?

The right answer is neither! Never have water just before exercising or immediately after exercising as long as you have a gap of 10 mins atleast you should be good! Although I prefer drinking water after exercise simply because chugging a lot of water before a workout makes me feel full and restricted of sorts. Hope that answers your question.
Good luck!

Both. I always end up thirsty while working out if I didn't drink a glass of water. So I drink a glass of water but I also do it after working out because my body is dehydrated.