Then you gotta take a rest. You can't be doing a lot of situps every single day. Think of it like this; when you do situps you "rip" your tummy muscles, if you don't give it time to heal back you're just going to keep hurting your muscles. Just be patient and give it time, you're six pack will eventually come. Btw you're gona need cardio if your fat (if you really are fat... No offense o-o) lol