Abstract: An exercise assistive device to help a developmentally delayed person, such as a child, develop vestibular balance and muscle control, so that the child can learn to perform mobility activities, such as crawling, sitting upright, standing or walking. The device includes a support frame having an upstanding base legs with a connecting frame extending therebetween. A body suit glidable support dolly is mounted upon the frame, and travels longitudinally, traversely and rotationally thereupon. The body suit is suspended from the suit glidable support dolly. Flexible connector straps are provided between the body suit and body suit glidable support dolly and made of a material such as reinforced fabric or canvas. These connector straps are positioned in spaced-apart relation to one another about the body suit glidable support dolly. The body suit is suspended from the seat-support leg by the connector straps that extend between the body suit and fasteners.