Preston graduated in 1977 with a Bachelor of Science in Business Administration and was awarded a Post-Graduate Scholarship by the NCAA. He was also selected by the New England Patriots in the NFL Draft that year and elected to forgo an MBA program to pursue a career in professional football.
The following year he landed in Denver Colorado, where he played for six seasons as a running back with the Denver Broncos. He earned Special Team MVP his Rookie season, and his most productive year came in 1981 when he combined for 1,150 yards rushing and receiving. During his years with the Broncos he was also very active in community activities, serving as Colorado Sports Chairman for Muscular Dystrophy. He was honored by the Boy Scouts of America for his community involvement, and nominated for the Miller High-Life NFL Man-of-the Year award in 1981. Preston is a Founding Board Member of Rebuilding Together Metro Denver, and he currently serves on the Denver Bronco Alumni Council.