I've talked about this before and shared a few HIIT workouts. I love HIIT more than an awesome CrossFit workout! Great for getting you through a plateau and great for your motivation because - This. Will. Yield. Results. But It will kick your butt first. =]
HIIT can be done with more than just cardio, it applies to lifting as well. Check out my HIIT 100 workouts!
The Workout:
Warmup with a 5 minute walk
30 second sprint
3 minute jog
30 second sprint
1 minute walk
REPEAT 3x
What HIIT workouts have you tried before?