Lennis Cowell began his coaching career as an assistant coach at Cal Poly and then served as an assistant coach and then head coach at Cuesta College. After being head coach at Hancock College, he took over as head coach at San Luis Obispo High School. He led Clovis West High School to two California Interscholastic Federation state championships and an 85-match winning streak, and was named Southern California Regional Coach of the Year in 1983 and National High School Coach of the Year in 1984.

He returned to Cal Poly as head coach, and led the team for 18 seasons from 1985-2003, compiling a 167-147-8 career record. He coached 14 Pac-12 Conference individual champions, eight NCAA Division I All-Americans and three top-five individual place winners at the NCAA tournament.

As a wrestler, he was a two-time NCAA College Division II All-American for Cal Poly, finishing third in 1965 and fourth in 1966 at 130 pounds, and wrestled on Cal Poly's first NCAA DII national championship team in 1966. He was also a two-time California Collegiate Athletic Association champion and an NCAA Regional champion.

Cowell was one of the greatest wrestlers ever to come from Contra Coast County. Competing for Pleasant Hill High School, he was a two-time league champion, a North Coast Section champion and a NorCal state champion. Cowell also excelled in football and baseball.

Cowell continued his support and loyalty to Cal Poly wrestling by coordinating and running a benefit golf tournament that raised more than $540,000 over 12 years.

He is a member of the Cal Poly Athletics Hall of Fame, the California Wrestling Hall of Fame and the Diablo Valley College Hall of Fame.

Lennis and his wife Denise have three sons, Shaun, Lance and Casey.