Lewis grew up in Hazlehurst, MS and went to Hazlehurst High School where he played Running Back. He attended Jackson State from 1984-1988. During his time at Jackson State, Tillman played in 43 games, had 830 rushes for 3,989 yards (breaking Walter Payton's career rush record), 30 rushing touchdowns, 29 catches for 212 yards, and 3 receiving touchdowns. He was a four-time SWAC Champion, three-time First Team All-SWAC, two-time Finalist for the Walter Payton Award, two-time Kodak All-American, and the 1987 SWAC Offensive Player of the Year.

In 1989, Tillman was drafted in the fourth round of the NFL Draft by the New York Giants. He spent seven seasons in the NFL, playing for the New York Giants and the Chicago Bears. Over his NFL career, he played in 109 games, gained 2,383 yards on 659 rushes, had 43 catches for 315 yards, 12 rushing TDs, and returned 3 kickoffs for 49 yards. He was also a member of the New York Giants Super Bowl 1991 Championship team.

In addition to being inducted into the Mississippi Sports Hall Of Fame, he has also been inducted into the Jackson State Athletics Hall of Fame and the SWAC Athletics Hall of Fame.