I had a C-Section 9 weeks ago and have healed well. My 6 week check up went well and I was given the all clear to exercise again. I need to as I put on almost 5 stone in pregnancy! 
Running has been going ok, better than I expected although obviously I'm no where near as fit as I was.
My problem is; I tried circuits today and I can't even complete one sit-up. I just have no strength in my tummy at all. My DH has given me some core exercises to try and help with this but was wondering if anyone has any good ideas on how to regain my tummy muscles. I was heart broken - not even one sit up - that's awful!!