If you just run on the treadmill. Then bring a towel, a big glass of water, plenty of water, a pair of loose pants, preferably sweatpants. If the gym has air conditioning, bring a vest or short sleeves. If there is no air conditioning, bring long sleeves, loose cotton absorbent, and wear a pair of sports shoes, preferably a mobile phone headset or P3. I used to listen to songs when I was running.

You can wipe it with a towel when you sweat. Running consumes a lot of water. By the way, adding less salt to the water can replenish water, but don't gulp it, drink more and listen to songs while running. This is very pleasant.

By the way, remember to bring a thick coat. Don't leave the gym immediately after running. Have a rest, then put on a thick coat and go out to prevent catching a cold.