McMillan first attended The John Carroll School in Bel Air, Maryland where he played football during his freshman and sophomore years.
Before his junior year, he transferred to North Harford High School,[1] where he played football, basketball, and ran track and field.
As a senior, McMillan led North Harford in rushing and earned a selection to the 1976 All-American Team.
[3] McMillan led the team in rushing with 1,002 yards and earned Maryland Junior College All-Region and All-State honors.
[5] Following his sophomore year at Harford, McMillan received a scholarship to continue his college football career at the University of Pittsburgh.
[7] McMillan and freshman quarterback Dan Marino led the Panthers to an 11-1 record and finished the season ranked number seven in the AP poll.
[8] Pitt had high expectations coming into McMillan's senior season, with the Panthers ranked #3 in the AP preseason poll.
[13] McMillan joined a Colts backfield occupied by 1980 first round draft pick Curtis Dickey.
[14] In the strike-shortened 1982 NFL season, Dickey suffered lingering injuries that provided McMillan more opportunities.
McMillan plunged for a one-yard touchdown run to tie the game late in the fourth quarter, giving the Colts their only non-loss of the season.
Under first-year coach Rod Dowhower, the team finished 5-11 and missed the playoffs for the eighth consecutive season.
[19] McMillan posted his best statistical season, leading the team in rushing for the third time, with 190 carries for 858 yards and seven touchdowns.
He split rushing duties with running back George Wonsley, as Curtis Dickey was sidelined with injuries before being released mid-season.
[22] While McMillan was away, the Colts traded with the Los Angeles Rams for star running back Eric Dickerson.
[24] Following the end to his professional football career, McMillan managed a health club in White Marsh, Maryland.