He continued his collegiate career in 1956, at Miami University in Ohio, where he broke the school record in the mile as a sophomore running 4:12.1.

In May 1960, he was assigned to Oxnard Air Force Base in California and Max Truex (himself a world class distance runner, who placed sixth in the Olympic 10,000 meters that year) became his commanding officer.

In June, after one month of good training, Schul ran the USA championships; he placed fifth in his trial race, running 3:55 for 1500 meters.

However, after several poor races that spring, Schul was diagnosed with mononucleosis and spent three months in an Air Force hospital.

With a partially torn soleus muscle, Schul placed third in the Pan American Games at 5K, but the injury kept him from competing in the U.S. Championships.

[citation needed] Schul posted an extremely impressive outdoor season in 1964, not losing a single race [citation needed] and beating among others Bruce Kidd, Gerry Lindgren, Billy Mills, Bill Baillie, and Bill Dellinger.

On August 29, 1964, Schul set a new world record for two miles of 8:26.4, eclipsing the previous mark of 8:29.6 by Michel Jazy of France.

In the last lap, Jazy appeared poised to take the gold, as he had opened up a ten-meter lead on the back stretch; however, Schul ran an impressive 37.8 for the last 300 meters on a muddy track.

Schul was employed at Wright State University in Dayton, Ohio, as its men's and women's cross country and track coaches from 1996 to 2007.