Are you in need of a new ab exercise?
Oftentimes, we fall into a routine and do the same exercises over and over.
Mostly, it's because we're comfortable with them, we know how to do them and -- let's be honest, here -- the thought of trying new stuff, can be intimidating.
Check out this link for a demo on doing jack knives. This is not a new exercise by any means, but it may be new to you!
Go ahead and give it a try, don't be scared.