Get your timers ready because this workout goes fast. Make sure you have some serious floor space (at least 20 feet)—sounds like a good excuse to clean out the basement, no?—or just sneak out of the house and do this workout at the gym.
This quickie circuit combines muscle toning and cardio for 12 minutes of fun (hell). Do as many rounds as you can before the timer's up.
5 Triceps Dips
Sit on edge of chair and place hands on edge just outside of hips. Walk feet out a few steps, slide butt off chair, and straighten arms. Bend elbows and lower body until arms are bent at about 90 degrees. Press down into chair to return to starting position.
10 In & Outs
Lie faceup with fingertips behind ears and legs extended. Lift legs until feet are about six inches off the ground. Engage core and lift shoulder blades off the floor like a crunch while also pulling knees in toward chest. Careful not to pull on your neck to crunch; use abs to lift. Reverse the movement to return to starting position.
20-Ft. Sideways Bear Crawl
Start on all fours with hands under shoulders, knees under hips and bent to 90 degrees. Tuck toes and lift knees to hover two inches off the ground. Press through hands to keep shoulders out of ears. Keeping core tight, move right arm and right foot to the right for 5 steps and then repeat to the left for 5 steps.