Here is the customized Ab Challenge. I tailored this one to accomodate people like me who have bigger middles and might have an issue doing regular sit-ups.

Day 1 - 20 Crunches/ 6 Leg Raises/ 10 sec plank
Day 2 - 28 Crunches/ 8 Leg Raises/ 12 sec plank
Day 3 - 30 Crunches/ 10 Leg Raises/ 15 sec plank
Day 4 - Rest Day
Day 5 - 42 Crunches/ 12 Leg Raises/ 20 sec plank
Day 6 - 50 Crunches/ 15 Leg Raises/ 25 sec plank
Day 7 - 60 Crunches/ 20 Leg Raises/ 30sec plank
Day 8 - Rest Day
Day 9 - 75 Crunches/ 30 Leg Raises/ 35 sec plank
Day 10 - 100 Crunches/ 30 Leg Raises/ 38 sec plank
Day 11- 120 Crunches/ 33 Leg Raises/ 42 sec plank
Day 12 - Rest Day
Day 13 - 135 Crunches / 40 Leg Raises/ 50 sec plank
Day 14 - 150 Crunches/ 42 Leg Raises/ 55 sec plank
Day 15 - 160 Crunches/ 42 Leg Raises/ 60 sec plank
Day 16 - Rest Day
Day 17 - 175 Crunches/ 45 Leg Raises/ 65 sec plank
Day 18 - 190 Crunches/ 48 Leg Raises/ 70 sec plank
Day 19 - 205 Crunches/ 50 Leg Raises/ 75 sec plank
Day 20 - Rest Day
Day 21 - 220 Crunches/ 52 Leg Raises/ 80 sec plank
Day 22 - 235 Crunches/ 55 Leg Raises/ 85 sec plank
Day 23 - 250 Crunches/ 58 Leg Raises/ 90 sec plank
Day 24 - Rest Day
Day 25 - 265 Crunches/ 60 Leg Raises/ 95 sec plank
Day 26 - 280 Crunches/ 60 Leg Raises/ 100 sec plank
Day 27 - 295 Crunches/ 62 Leg Raises/ 110 sec plank
Day 28 - Rest Day
Day 29 - 310 Crunches/ 62Leg Raises/ 115 sec plank
Day 26 - 325 Crunches/ 65 Leg Raises/ 120 sec plank