You can do something similar to riding a bicycle in bed, lie on your back, and then kick your legs in turn. Of course, you can also lean your head against the bed, so you will lose face. If you can persist, it will be effective in one month. Of course, it's best not to lie down or do strenuous exercise just after eating, preferably after an hour. It is best not to sit down after a meal, but to stand on tiptoe, which can prevent fat accumulation.