I am on my way to rock hard abs and besides crunches what else can achieve that ?
planks will be your best friend.
trust me. )
Do you have a pilates ball? I use that and to get real definition I have a heavy punching bag.
Planks, russian twists, it's good to mix things up and challenge the muscles in different ways.
3 sets of 17 chin *ups in 15 minutes ~~