I have just signed up for sweatflix. I have purchased the bodyrock challenger bars, weighted vests etc. I need to lose weight and get in shape, but the immediate issue is that I really lack a core, so I have a lot of back pain. I mean there is nothing going on in the ab area at all, except fat. It hurts to stand too long or lift or lean over too much. I'm 5'4" and 165 lbs. I'm pretty strong everywhere else (but in no way muscular or toned, just no pain or issues) I'm looking for tips on where to start and which videos or exercises would be good to start building my core so I can alleviate the back pain which will allow me to do more. Any advice would be greatly appreciated.