McManus began his career playing football in the fourth grade at St. Mary's of Buffalo Grove, Illinois.
Following McManus's high school career, he would go on to play football at Boston College under Head Coach Tom Coughlin.
During McManus's senior year at Boston College, he was a third-team All-American along with being a two time First-team All-Big East Linebacker.
He was signed as an undrafted free agent by the New Orleans Saints in 1993, even though he played his entire career for the Jacksonville Jaguars.
McManus currently resides in Jacksonville, Florida with his wife Kristina and their three children Avery, Kelsey and Harley.