weed does affect people in different ways than others. I, for one, can not smoke on a 90+ degree weather, because my body can't handle it. I get all light headed and feel out of the norm. I can smoke and chill in an air conditioned room, but i can't go out in the blistering sun and do my daily activities(play b-ball, jog, etc.). The weed plus the sun will wear me down quickly, but if i'm just walkin and i'm high i'm good.
I'm sure attempting to work out while i'm high wouldn't be a good experience, but people can do it.