He began his coaching career at high schools in Norwich and Massapequa, New York before moving up to the college level. Lotz served as an assistant coach for the North Carolina Tar Heelsmen's basketball team of the University of North Carolina in Chapel Hill, North Carolina under head coach Dean Smith from 1965 to 1973. During his eight seasons with Smith's Tar Heels, the team made four appearances in the Final Four of the NCAA Tournament. Lotz became the head coach of the Florida Gators men's basketball team of the University of Florida in Gainesville, Florida, a position he held from 1973 to 1980. Lotz's 1976-1977 Gators finished 17-9 overall, and 10-8 and in fourth place in the Southeastern Conference, and he was recognized as the SEC Coach of the Year in 1977. That, however, would prove to be his only winning record in conference play. Following a 4-7 start to the 1979-80 season, Lotz was fired. He finished his seven-year tenure as the Florida Gators' head coach with an overall win-loss record of 83-88 and 46-66 in the SEC.
Life after basketball
After his coaching career ended in 1980, Lotz returned to Chapel Hill as an assistant athletic director at UNC and directed the University of North Carolina's community outreach program. He involved hundreds of North Carolina student-athletes in various volunteer projects, including the Thanksgiving food drive for underprivileged families, the Juvenile Diabetes Walkathon, and clothing collections for the needy. Lotz received the Governor's Award for Excellence for Crime Prevention in recognition of his work with youth in Chapel Hill and Carrboro. Lotz died in Chapel Hill on May 5, 2001, after a brief fight with a malignant brain tumor; he was 64 years old. He was survived by his wife Vicki and their two daughters. The Fellowship of Christian Athletes inducted Lotz into its "Hall of Champions" in 2001. In 2003, the FCA established its annual John Lotz Barnabas Award to "honor a basketball coach who best exhibits a commitment to Christ, integrity, encouragement to others and lives a balanced life"; past winners include John Wooden and Steve Alford. The Chapel Hill Police Department named its summer basketball camp in Lotz's honor.
