I'm not a trainer or anything. But over pushing yourself is not good. You can tear your muscles, they can also go into a sort of shock of not being use to such a workout, and be in so much pain that you can't even work out. Start with about 20-30 if you can... Maybe 4-5 times a week. And when you start getting use to that, you can add another 10 or so.. And so forth. Last year I wanted to put more definition to my what was becoming a bit of a stomach and I did about 40 sit ups the first night, 50 the next... I felt like superwoman having never worked out. Another 40 the next day... My step dad gave me shit and was like "you're not suppose to do so many! Plus in 3 days in a row!" I tole him no no I feel fine. The next day... I definitely paid for it! I couldn't laugh it hurt so bad. Still kinda felt good coming from a person who likes bruises, but just go easy on yourself to begin. Then you can up your numbers as you go.