"All the energy you put in, you get back manyfold more through the metabolic and mental benefits of exercise," Holtan told Business Insider. "As soon as I really realized what this was doing for me physically and mentally, I wanted to implement this for patients too." Her patients at Roswell Park Comprehensive Cancer Center in Buffalo, New York receive stem cell treatments for conditions like leukemia - a grueling procedure that can require months of recovery time in a hospital.