Size: Depending on your go-to gym activity, you may have more to bring along with you than others. If, for instance, you’re packing work stuff, sneakers, a change of clothes, a water bottle, a basketball, and the like, you’re going to want a bigger bag. Stick to the basics, though, if you’re more of a “water bottle, deodorant, and fresh tee” kind of gym-goer.

Pockets: Again, considering how much you bring, you'll likely want at least a pocket or two so you can at least keep things somewhat organized. A spot for your phone, wallet, and water bottle, most notably, are important things to consider. If you're a super sweater, or your activity of choice requires returning home with wet clothes, i.e. spending time in the pool or sauna, you also may want to consider a backpack with a separate waterproof pocket.

Material: Waterproof materials or even mesh will keep things from getting everything wet or even help them dry faster. Should you require this — particularly if the backpack will be used outdoors for hiking, where rain can really put a damper (pun intended) on the experience, opt for waterproof.