Before joining the the Mount, Kellinger spent the last nine years coaching at Centennial High School in Ellicott City, MD. He led the Eagles to a 71-36 record over seven years as Head Coach, including a Maryland Class 3A Regional Championship in 2018. Kellinger has also been a coach and administrator for The Roughriders lacrosse club for the past six years.

Kellinger currently works at Corrigan Sports Enterprises, as a Marketing and Event Manager, where he works closely on lacrosse properties such as the Under Armour All-America.

As a player, Kellinger was a two-time high school state champion goalie in 2002 and 2003 and Varsity walk-on at the University of Maryland in 2007 and 2008.