The present invention is a device to simulate balance and motion activities of a user in response to the user's movements. The device has a curved sloping base with a top central area, a user support portion with a top and a bottom, a plurality of rolling elements coupled to the bottom of the user support portion, and a resilient element biasing the user support portion towards the top central area of the curved sloping base. The orientation of the user support portion relative to the top central area of the curved sloping base is responsive to movements of the user. The device provides a simple easy to use way to simulate balance and motion activities and thus condition and train a user conveniently and efficiently. The device conditions muscles in the legs and trunk as well as the balance mechanism while increasing endurance.