Born in Gainesville, Florida, Muir attended Brown University, where he earned a bachelor's degree in organizational behavior and management and played basketball, serving as the team's co-captain in his senior year.
[1][2] He went on to earn a master's degree in sports administration from Ohio University.
[2] Muir worked as assistant director of the NCAA Men's Division I Basketball Championship and then joined the staff of Notre Dame athletic director Kevin White.
[1][2] In 2012, following the departure of Bob Bowlsby to head the Big 12 Conference, Stanford chose Muir as its seventh athletic director.
[1] In December 2014, Muir was announced as one of the six recipients of the 2015 Silver Anniversary Awards, presented annually by the NCAA to outstanding former student-athletes on the 25th anniversary of the end of their college sports careers.