I must think to breathe: a personal experience

A 97-year old man is largely healthy, but his respiration is altered. He breathes normally and effortlessly while sleeping or sitting. But if he stands, walks, or engages in other activities that require him to concentrate on coordination and balance, breathing becomes a conscious effort. He stops breathing and grows faint if he does not remember to breathe. This condition compounds other challenges of aging, but he is determined not to allow it to limit his activities. He speculates that his condition results from age related deterioration in the autonomic nervous system, most likely the breathing centers in the brainstem.