At ProjectMe, we love Tabatas.  We  won’t go into all the science here, but there’s a great article on the full background of Tabatas, developed initially for Olympic Skaters.  20 seconds of high intensity work with 10 seconds of rest.  Repeated between 6 to 8 times!  Make sure you’re ready for trembling muscles and burning lungs.  Check out a great tabata workout here http://greatist.com/fitness/best-tabata-moves.

If you want a great Tabata timer for your smart phone, check out http://www.tabatatimer.com/.

Beginner Intermediate Advanced
Run/Walk Power walk / Jog Sprint runs / high knees: Fast sprints
Burpees step back to plank full burpee Single leg burpee with jump
Squat Air squats Squat jumps Deep squat jumps
Lunges holding chair walk lunges Jump lunges
Jumping Jacks side steps with arm swing Jumping Jacks star jumps starting crouched
Push ups incline on table or chair Regular pushups jump clap pushups or one legged