Sorry, not trying to hijack just help.
Monster, (or anyone)
here is a great video for core strength. I used it after the kid was born, and still use it today, 9 years later! I love it. It has two 20 minute sessions. The first time I did it, I could barely do most of the moves of the first session alone for the length of time that she did. The next day I could hardly breathe I was so sore. Worth every penny!