A device for use in a shoe includes a first foot, a second foot, a third foot, a fourth foot, a first flexible leg, a second flexible leg, a third flexible leg, and a fourth flexible leg. The first flexible leg extends from the first foot and is curved. The second flexible leg extends from the second foot and is curved. The third flexible leg extends from the third foot and is curved. The fourth flexible leg extends from the fourth foot and is curved. The first flexible leg, second flexible leg, third flexible leg, and fourth flexible leg are joined together with each other at a common area. The first flexible leg, second flexible leg, third flexible leg, and fourth flexible leg are configured to store energy when a force is applied to the common area, and to return energy when the force is removed from the common area.