Walking itself enables many of the small muscles that are important for proprioception to work properly. In addition, the deep, stabilizing muscles are mainly used. Walking carefully – without neck brace – and on many different grounds, for example streets, sand or forest ground, teaches the body and all muscles along the spine to balance, and they therefore stabilize the spine. Moreover, walking is gentle on the joints, easily accessible, and achievable for most people.
I am currently using a tracking device to count my steps for personal motivation. I can program it with a daily goal, and then try to reach it. Of course, that does not work every day (not even half the time I reach my goal) but it helps me to stay active even with all my symptoms, and prevents my muscles from weakening.