You need a strong base if you’re active walking, biking, dancing, or running. Your base is your feet so you need to strengthen your trotters to prevent injury. Here’s a fun way to strengthen your feet using marbles: Place 20 marbles on the floor. Pick up the marbles one at a time using your right toes

and drop the marbles into a small plastic bowl. Repeat this pickup game with your left foot. I suggest a plastic bowl since it muffles the clank of marbles dropping into the dish.Try to play footsie marbles at least once a day. Source

Here is the original:
Strengthen Your Feet With Marbles