My dad said this very thing. He worked in construction and had a few friends who tried to never retire. The saw a lot of their friends die quite quickly after retirement, and the theory was that it was due to shear boredom.
I suppose that happens to people who are so unimaginative that they cannot think of a single thing to do when given the opportunity and must be told what to do by someone else (i.e., work).
Pity.