In the past four decades, Dick Hoyt and his son, Rick, who has cerebral palsy, have together completed six Ironman triathlons, more than 70 marathons and a 45-day run and bike across the U.S. without a single day of rest. Dick, 74, a motivational speaker and Holland, Mass. resident, is usually quick with a tale and a joke in his thick Boston brogue. But ask the former Air National Guard lieutenant colonel the most difficult thing he’s ever done, and he’s briefly rendered speechless. Read the full story on NowU.com (or download a pdf).