That won't help too much. If you want to tone your body you have to continually increase the amount of work your body is doing. So after a little while (a week or two) 100 push ups and sit ups won't be doing you any good. You'd have to increase the amount you're doing, which after some time will take forever. The best way is to do weights, easy for the arms but no so easy for the abs. My gym has an ab machine where you can increase the resistance, maybe you should try finding something like that. But a HUGE part to get ripped abs is your diet. You can have rock solid abs but can't tell if there is fat over top of them. I would suggest diet and exercise together, but be careful how you do it...don't go overboard. Your body still needs a lot of calories if you're going to be working out.
