Air movement promotes the evaporation of sweat, so a fan can help. Sweating also makes you thirsty because it boosts the concentration of salt in your blood, stimulating the thirst mechanism. But don't wait until you are thirsty to drink water, especially when you are exercising, it may be too late. If you don't replace enough water loss, you'll sweat less and your body temperature will rise. And the more fit you are, the more easily you will acclimatize to the heat.
Older people have more of a problem in the heat.
The bottom line is to drink lots of fluids before, during and after exercise. I'm Dr. Art Mollen.