A fan. A small fan loaned to me by one of the housemates during the last heat wave, the one that broke records and killed people. The "Heat Dome." That heat wave. The point is, it's hot again, though not the "warmest temps in Portland's recorded history" hot that I lived through in June...
...and I'm combatting that with a small fan. And it helps.
Just the little bit of air movement helps. It means my bedroom's air is circulating in a way it wouldn't do on its own. There's potentially much different air each time I breathe. It at least seems fresher.
I left the fan on overnight, then this afternoon let it run while I rested. I did so before it got warm or overly stuffy in my room, and later I noticed that — hey! yay! — I was more comfortable.
Air movement's important. At this house, I've developed the good habit of waking up on days that are going to be hot or at least really warm, and opening the front door. I'll also open the back sliding door at least a little bit, so the house cat can't go out unless another housemate decides it's okay to let him out, and get some cross-circulation. I do it for long enough that I usually can knock down the interior temperature by at least three degrees Fahrenheit, sometimes more. And sometimes I add a fan, moved to a certain spot, to encourage that cool air to get farther in.
Air. I can do good stuff with it.