Get your heart pumping and your arms and abs firing with this elevated version of a mountain climber.
Start facing the couch cushions, and place your hands on the seat of the couch, directly under your shoulders, arms extended. Walk both feet back out to a plank (top of a pushup) position and brace your abs in tight.
In a quick, controlled motion, begin alternating 'running' one knee in towards your chest at a time, keeping your shoulders steady over your hands the entire time.
Do this as fast as you can for one minute.
