Marvis was a highly touted prospect and among the top-ranked amateur heavyweights. He was the 1979 National Golden Gloves Heavyweight Champion and 1980 National AAU Heavyweight Champion. He was coached partly by his father, and in part by Georgie Benton and Val Colbert. "My dad tried not to play too active a role in my career for fear of putting pressure on me," Marvis said. Benton said that Marvis was a model kid. He grew up "like he was poor". According to Benton, "there were no favors. When the grass on the Fraziers' two-and-a-half acre plot needed cutting, Marvis did it. With a hand mower. He goes to choir practice Monday nights, Bible study Wednesday nights and church on Sunday. He doesn't smoke, drink or run around. Not because such strictures are demanded of him, but because that's the way he is boxing or no boxing."