Think you know how to do four of the most basic exercise moves?
Chances are, you need to brush up on your skills.
While the pushup, crunch, squat and lunge are standard workout routines that burn calories and tone your physique, they are also frequently done wrong, making them ineffective and potentially painful.
Fortunately, there it's easy to learn to do each one like a pro.
Trainer Ben Greenfield, an expert in fitness, nutrition and sports science, shows how you can master them all without pulling a muscle.
Add some spring to your step and check out his techniques above.