How little exercise can you get away with?

Cantarians and near-centarians like Warren Buffet, Charlie Munger, Jimmy Carter and Henry Kissinger: They did't stop puttering around. If we're optimizing for lifespan the rule is simply to keep moving.

My Grandpa was a railroad engineer, he retired a strong, healthy man at 65, sat down on the lazy boy and wasted away, he died at 74. My Grandpa's younger brother was a farmer, he had no retirement plan, he worked that farm until he was 88.