This bag is with me at all times, so it is a big part of me. So, here's what I've got inside:
In the main pocket, since I'm usually coming from work or something else, I carry my gym clothes with me. I have my sports bras, tank top, capris, a water bottle, 2 weight books, a towel that I use for the spin classes, my knee brace and a jacket.
The small front pocket, I have my mp3 player, extra batteries, my lock (for the lockers), a hair clip, pony tail hair bands, the big band that goes around your entire hair (to hold it back), some energy packets and of course my chapstick.