There is really no such thing as time. As long as you want to exercise, it is never too late. What you are afraid of is giving up halfway or giving yourself various reasons. There are many people in their twenties and thirties, even those in their fifties and sixties. In fact, don't ask others if they can do something. If they tell you it's too late, will you give up? Therefore, if you like and keep exercising, abdominal muscles will always appear. If you don't want to exercise every day and just want to have abdominal muscles, then your stomach can only be a piece of fat, not eight abdominal muscles. So, since you want abdominal muscles, exercise. Keep exercising for more than half an hour or an hour every day, and you will find obvious changes after a while.