Because Joseph Pilates had experience in fitness, it enabled him to develop his work.
He studied various self-improvements systems. He drew from Eastern practices and Zen Buddhism and was inspired by the ancient Greek ideal of man that is developed in body, mind, and spirit. He studied anatomy and developed himself as a bodybuilder, wrestler, gymnast, boxer, skier, and diver.
The dance community depended on the Pilates method of training for the strength and grace it developed in them and its rehabilitative effects.
Dancers and elite athletes kept his work alive. When science caught up with the Pilates exercise principles in the 1980s, it lead to the surge of interest in the Pilates we have today.