Stanforth ran his first marathon in 1973. While in the Army, he ran the 1974
Boston Marathon, finishing 75th. and set a course record in a race at Cooke Field, the stadium of the
University of Hawaiʻi at Mānoa. In 1978, Stanforth moved to
Phoenix, Arizona to attempt to qualify for the
1980 Summer Olympics. The race was run in a peak temperature of over , and Stanforth caught the leaders around into the race as they were struggling with the heat more than him. He then passed
1977 winner Dan Cloeter, Stanforth was invited to the
1979 Chicago Marathon, but did not compete due to an injury. He competed in the US Marathon Trial Event for selected for the 1980 Summer Olympics. During the race, he became dehydrated, and eventually finished 124th out of 125 competitors. ==Coaching career==