What's in your gym bag?

Hey everyone! I recently joined a gym, and I've officially gotten through one week of training! I'm going to the pole studio once a week, as well as yoga once a week. For getting my membership with this gym, I've also been given a gym bag! However, I don't know what to put in it!! Literally the only thing in it are a pair of shoes (because my gym won't let me wear normal shoes, or no shoes!) and my water bottle. For pole time, I can think of a few more things to bring- my heels, and shorts. I don't really use pole grip (though maybe I should one of these days?) and for yoga, literally the only thing I need is my yoga mat... So, for those who go lift heavy things, what do you bring in your giant gym bag?! I need ideas! I already figure I'll bring a towel (apparently I sweat a lot now) and some spare socks, and maybe a spare shirt or something... but, otherwise, what can you just not live without?