Well, I am the least qualified person to talk about this, but I get emails everyday from a diet website (haha!)
They say...instead of doing crunches, lift your leg instead. You are still working your core, but it's working the bottom part of it.
You go...90 degrees...then 45 degrees...then 25...etc...but dont ever let your legs touch the floor. You have to hold it.
wow...i wish I have your dedication, Minh! I admire you for doing that.
Albert, I thought when you get married, the fatter you get?