EnchantedEva > Status Update

I need yalls help. I need an ab workout that actually WORKS. I would prefer it to be relatively simple, and not super long. Also, nothing with weights, as I don’t have access to those. I really need to lock in on my ab strength for karate tournament training, but the sit ups my Sensei has us do just aren’t cutting it for me. So, if you have one that works well and fast, please share!