I saw a method on the Internet, and now I'm experimenting with it myself, that is, sitting in a chair (because I basically sit at work), with my thighs and calves at a 90-degree angle, raising and straightening one leg slightly higher than the knee of the other leg, hooking my toes up, repeating 10 to 20 times, and then doing the same with the other leg. Now I insist on it twice a day, once in the morning and once in the afternoon, regardless of whether it works or not.