There are people who do amazing things, and some just don't know when to stop.
Take the 48-year-old blind athlete extraordinaire Rob Matthews. Neither age nor disability is slowing him down. In fact, the pace is picking up, to what might be called extreme degrees.
The Englishman, now married to a New Zealander and living in Auckland, has a string of Paralympic running achievements on his CV that mark him down as a legend in this arena, and a prized MBE awarded to him by the Queen in 1987 for services to disabled sport.
A potted biography on his website explains: "Rob has driven a racing car at high speed at Brands Hatch, he skis and plays golf, football and cricket."
The Rob Matthews catch-cry should be: "But wait, there's more."
His next race is the Auckland half marathon on November 1, where he aims to run 1hr 22m and break his own race record for a blind runner.