The most decorated runner in UM history, Sullivan was a 16-time Big Ten champion and a 14-time NCAA All-American during his Michigan career. He won four NCAA titles, claiming top honors in the mile (1995 and 1998) and the distance medley relay (1995) during the indoor season, and the 1500m run at the 1995 outdoor championships. Sullivan was a nine-time Big Ten Athlete of the Year, earning the honor each of his four years in cross country, three times in indoor track and field and twice outdoors.

Sullivan was a three-time Olympian for Canada, competing in the 2000, 2004 and 2008 Games. He placed fifth in the 1500m run at the 2000 Olympics and is Canada's record holder in three events: 1500m (3:31.71), mile (3:50.26) and 3000m (7:41.61).

In just his second season leading the Maize and Blue, Sullivan coached the team to its first sweep of the Big Ten and NCAA Great Lakes Regional titles with a top-10 NCAA finish since his senior season in 1997. U-M placed ninth at the national championships, the program's best finish since 2003.