"Whether I've done a particularly hard strength workout and my muscles are sore the next day or I'm stiff from sitting at my work desk, these Zongs Massage Ball Rollers ($12) are a true gift. They're simple to use, get into any deep knots, and offer relief when I need it most. Plus, if your significant other, friend, or family member isn't so eager to give you a massage, this will make it 10 times easier for them — the rollers basically do all of the work!" — Sam Brodsky, assistant editor, Fitness