Closer to home, the so-called aerobic exercise, as the name implies, is to exercise under aerobic metabolism, and consume excess fat in the body through exercise to achieve the purpose of losing weight. However, 15 consumes glycogen 20 minutes before aerobic exercise, and starts to consume fat after 30 ~ 40 minutes of exercise.
So my plan for you is to do spinning or skipping for 40 minutes every day, and then exercise with abdominal muscles, and the effect will come out in one month. I wonder if your sit-ups are the kind of help on TV. If so, don't use them. They have no effect at all. It's really good to practice sit-ups and belly rolls honestly.
Abdominal muscle reference video: /v_show/id_XNTY5MDk5MTg0.html
I hope I can help you.