Marsh was the starting running back at Wallowa High School, contributing to the team's Tu-Valley football co-championship in 1957,[1] which was a three-way tie with Enterprise and Union, but only Wallowa advanced to the state playoffs after a vote by the league's school superintendents.
As a sprinter and long jumper in track, Marsh helped Wallowa win the 1957 State Class "B" title.
Marsh accepted an Oregon State University track and field scholarship, where he competed as a sprinter, hurdler and a broad jumper.
Marsh was signed as an undrafted free agent by the Dallas Cowboys after the 1961 NFL draft, because they were impressed by his speed.
He was eventually moved to fullback to take advantage of his size and speed, while splitting time with J. W. Lockett.
In 1962, he played fullback alongside Don Perkins, ranking seventh in the NFL with 802 yards and a 5.6-yard average per carry.
The play came against the Philadelphia Eagles, when the Cowboys became the first NFL team in history to produce two 100-yard plays in the same game: a 100-yard interception return for a touchdown by strong safety Mike Gaechter and the 101 yard kickoff return for a touchdown by Marsh.