Shields grew up in North Bay, Ontario, playing minor hockey until bantam level with the local Athletics AA program of the NOHA.

At age 16, Shields moved to southern Ontario to play for the St. Marys Lincolns Jr. B club of the OHA, before accepting a scholarship to the University of Michigan.

In his NHL career, Shields would play for the Buffalo Sabres, San Jose Sharks, Mighty Ducks of Anaheim, Boston Bruins, Florida Panthers, and Atlanta Thrashers.

With Hašek leaving in the midst of game three of the first round, Shields was forced to step in but he helped the Sabres to rally and defeat the Ottawa Senators.

Shields served under Mel Pearson as a volunteer assistant coach at Michigan Tech for two seasons from 2011 to 2013 before joining the Florida Panthers as a goaltending consultant in the summer of 2013.