People often overlook bodyweight exercises because they think they're not hard enough. But you CAN build muscle and strength using your own bodyweight, especially with this intensification method.

The Darden 30-10-30 Method: Split Squat

To give you an idea of how brutal this one can be, take a look at the video and keep in mind that this is a pro football player who squats over 500... and he's not able to finish the last 30 seconds with bodyweight only!

This method focuses on making a set more difficult by lengthening the duration of the eccentric phase of a movement.

1. Start by doing a 30-second long eccentric (lowering) phase, then immediately do 10 normal reps. Still control the eccentric on the normal reps – two seconds down is a good target.
2. After your tenth rep, finish with one final 30-second eccentric, after which you may or may not try to stand up. My guess is that you won't be able to do it.

Is 30-10-30 too easy for you? Just do 15 or 20 reps instead of 10.