For 27 years, from 1966 until 1993, Stack persisted in covering a set training route. His highly visible training routine made him a San Francisco institution. "I'm going to do this 'til I get planted," Stack decreed. Starting on his bike, he would ride six hilly miles from his Potrero Hill home to Fisherman's Wharf. Once there, he'd strip off his shirt, displaying tattoos of peacocks, wild horses, and bathing beauties across his broad chest, and then proceed to run a route over the Golden Gate Bridge to Sausalito and back, after which he would take a one-mile (1.6 km) swim in the currents of the San Francisco Bay near Alcatraz Island. He trained on the course and competed in the venerable (first run in 1905) and arduous Dipsea race. It is probably noteworthy that Stack could claim that he was the only actual 'prisoner' of Alcatraz Island to have made a successful swim from Alcatraz to the shores of Fisherman's Wharf - Stack was a prisoner on Alcatraz for a six-month period sentenced to hard labor while a youth, for having left his post, Absent Without Leave (AWOL), in the Philippines. He had in fact swum the distance many times in his later years, as a participant in sanctioned Alcatraz swims which have become quite popular. He often swam year round in those cold Bay waters.