17 Gadgets Fitness-Lovers Will Love to Unwrap This Year

This one's for the friend who says they can plank for five minutes straight. Challenge them to try doing it on the Stealth Core Trainer ($129), which connects to the Stealth Fitness app on your phone to turn your planks into interactive games. You'll move forward, backward, and from side to side on the board, upping the intensity of any plank. Our reviewer called it "a fun tool to increase your core strength and get in an effective challenge that also works your mind-body connection."