I have started my own 300/30 Day Ab Challenge!
Basically, I started on January 30th and have been doing 300 ab workouts per day. An example would be: 25 sit ups, 25 left crunches, 25 right crunches, 50 bicycles, 25 Russian twists, 50 crunches, 25 reverse crunches, 25 in & outs, 50 Russian twists.. and then the next day do another 300 but mix it up.
The first two days I was alittle sore the next day, but to me, when you can feel the burn while working out, or are alittle sore after or the next day that lets me know I am changing how my body looks.. which is the point.
I am also doing leg workouts throughout the week, and 2-4 days a week I go walking around the golf course, which is two miles.
At the end of my 30 days I will post a before and after, to see how well it works, fingers crossed that I get a good result!!!
Stay in touch to check on my process :)