Walseth was born in Aberdeen, South Dakota, and an all-state basketball player at Pierre High School, graduating in 1944.
Following his graduation, he stayed at Colorado to earn a master's degree and coach the freshman team.
[1] Walseth moved to the college ranks the following season as he was named head coach at South Dakota State.
In the 1955–56 season he led the team to the North Central Conference championship and a berth in the 1956 NAIA Tournament.
This performance helped Walseth earn the Colorado head coaching job when his former mentor Bebe Lee was named athletic director at Kansas State University.