There is another way, sit up straight, straighten your legs (tighten your legs and spread them at a 45-degree angle), and then lie down, first with your left hand to your right toe, and then with your right hand to your left toe. Alternate 20 groups, get used to it and then gradually increase.
I'll do it when I'm free It's simple. I can do it while watching TV. Very convenient. Before you know it, your legs are thin. The second seems to be able to slim down.