If You Do 1 Workout, It Had Better Be This
Build muscle and blast calories with this effective bodyweight workout. And it's excuse-proof, too, because you can do it anywhere since it requires no equipment at all. The workout should take you around 20 minutes, so get moving!
Directions: Start with 10 reps of each exercise, building up to 15 reps of each move as you get stronger.
Here's a printable version of this workout. Now you really have no excuses!