Lehman served as the Thornapple Kellogg High School wrestling coach for 37 years from 1972 to 2009. In his tenure as coach, he amassed an incredible 710 wins, 234 losses and seven ties. In 2009, he was one of only six high school wrestling coaches in the country to reach 700 wins.
He was inducted into the Michigan Wrestling Coaches Hall of Fame in 2009 with a record of 19 league championships, 13 district championships, 9 regional championships, two state final appearances, one state championship, and nine team state qualifiers. He was 11 times the Regional Coach of the Year, four-time State Coach of the Year, and three-time National High School Coaches Association Coach of the Year finalist. He was a USA Michigan wrestling coach for 36 years, earned two national championships and five runner-up finishes and was selected as "Michigan vs. Japan" cultural exchange twice.
In addition to wrestling, he served as assistant football coach for 31 years and junior varsity softball coach for two years. He taught physical education at TK for 37 years and served as athletic director for six years. He was also honored as one of the coaches honored on the TK Wall of Fame located in the high school athletic lobby.