Well, there are many ways that you can defeat the heat. First, there are always the ice baths, but those are typically only worth it after exercising.
There is also ice cream. When it gets too hot, I try eating as many cool/cold things as possible. It makes me feel cooler inside. That sounded weird, I know, but it's true.
Use ice packs/bags too. I try icing myself all over the place, especially at the neck and abdomen. I don't know why, but my neck and abdomen are always the hottest points on me. It may just be me, but it also may be because those are the places where people's bodies emanate heat from. Don't keep it on your neck for too long, though, because I don't know if it is healthy to ice your neck like that. Just keep the ice pack/bag on for about two to three minutes, then shift it to another spot.
And then there's the AC. AC is energy and money consuming, but it is the quick fix. I prefer fans because they are much more eco-friendly, and although they take a bit of time to start cooling the room down, they help a lot, especially if you are sweating or have water on your body (you should probably wash the sweat off because it's bad for your skin and you get dirtier too!).
One more thing. I keep hydrated. That not only makes you cooler, but it also helps keep you healthy. Dehydration is very dangerous in the heat, so you want to drink as much water or other beverages as possible. Water is the best though.
So there you have it. HOW TO DEFEAT HEAT! <- that rhymed!