Born in 1946 in Minnesota, Sheldon grew up on the Lower Sioux Indian Reservation being the youngest of eight children. He attended the Institute of American Indian Arts in Santa Fe, New Mexico and the Ray-Vogue School of Design in Chicago, Illinois from 1965 to 1969. Drafted into the military in 1969, he served in Vietnam and was awarded the bronze medal while there. Returning home, he worked at the Walt Disney Studios in Southern California as an artistic consultant, developed displays for the New Disney World in Florida and various Disney movie productions, and participated in numerous art shows with the Disney organization. In 1976 he moved to Hawaii, attending the University of Hawaii. Shortly afterwards he made his television acting debut on Sesame Street (1969), where he was a featured actor for four years. Returning to Los Angeles, he affiliated with the American Indian Registry for Actors and participated in many of their productions. He appeared in two feature films: Dances with Wolves (1990) and Son of the Morning Star (1991), co-starred in an episode of "L.A. Law" and in "Miracle in the Wilderness".