It is unfortunate to hear that this is that case, yet it is encouraging to hear that he/she has not lost heart. It is very difficult to prescribe a physical workout to some who cannot move his limbs and is debilitated with other ailments. The one thing that can be prescribed is a formula for keeping happy, cheerful and hopeful. Those are the ingredients which will keep his spirits going and his body and heart alive!
Encourage social interactions on whatever level, as well as silent activities like reading, listening to music, taking up a hobby, given the confines of the ailment. On a purely physical plane, he can do some seated stretches and joint rotations to ease stiffness and lubricate the body. Keeping the mind occupied, the body supple and the spirit alive, he or she can find more meaning in life and will be able to overcome whatever is in store, with elan.