My 10 years old son is hyperactive in playing, sports,all day like jumping running ,very good in running ,suddenly I came to know he has both feet flat. At home he didn't wear slippers ,shoes ,wear shoes while playing outside only. At his age very difficult for me to make him doing leg stretch exercises for flat feet. I have one flat feet. I knew this problem will increase by age n weight gain. Right now he has slim body. Sometimes he has leg pain but he ignores. What I can do to develop his foot arch. Please suggest n advice.