Brennan was the Varsity Golf Coach (2003-2004) at The Marymount School in Manhattan, New York, and the Boys Varsity Golf Coach (2008-2011) at Saint Rose High School in Belmar, New Jersey.
Brennan was the Captain of the Seton Hall University Golf Team and played in the first ever Big East Conference Championship Tournament in 1980. Also played on the soccer team while at Seton Hall.