Work hard, get sweaty, and get done in 15 minutes. Sound like the perfect workout plan for you? We thought so. If you're ready to kick off 2015 with fresh strengthening moves that tone your muscles in a hurry, look no further. Simply check out these 15 workouts that you can crank out in 900 seconds (a.k.a. 15 minutes), and click the graphics for full how-tos for each move. So what are you waiting for? It’s January 1, and it's time to start sweating!