Leiszler graduated from Harvard University in 2003 with a degree in biology. He finished medical school at the University of Kansas School of Medicine in 2008.
After his residency with the University of Colorado (HealthONE Rose Medical Center) Program (2009-11), Leiszler did a sports medicine fellowship with the University of Colorado Hospital in 2012.
Leiszler was on the faculty at the University of Colorado Hospital, splitting his time between primary care family medicine and sports medicine, for two years (2013-14).
A native of Derby, Kansas, Leiszler was a varsity letterwinner as a running back on the football team at Harvard. He ran for six touchdowns and 483 yards during his sophomore season. Leiszler was projected to be the starting running back as a junior, but he suffered a career-ending repeat ACL injury before the season started.
Leiszler and his wife Tori are parents of two children: Teegan and Tana.