Sit-Ups Everyday

Every morning and afternoon I'm doing ten sit-ups. I'm so jealous of my friends who don't have to wear girdle everyday because they don't have belly fats. I have three babies and since I gave birth I didn't lose my pregnancy fats. If others can why can't I? I need to find out how how to get rid of belly fat fast. So I decided to be consistent with my daily exercise and I will never miss it. My belly is sore.My husband it's the muscle that hurts because I have done sit-ups for a long time. I'm also doing my shape-ups exercise. My thighs and legs are sore but I'm not giving up. No pain no gain. my goal is to be fit before this year ends.