"I'm letting go of my studios because I can't handle it," Winsor, 65, tells PEOPLE. "I'm very tired all of the time, and I don't have the strength. I don't have my upper body and my voice."
Despite suffering from the progressive neurodegenerative disease, Winsor still meets with some clients and talks them though the motions.
"With or without my physical body, I've always had the ability to look at someone's body and tell them what they need to do," she says. "That comes with time and you have to be patient."
Being diagnosed with ALS in 2013 has changed Winsor's perspective on life.
RELATED VIDEO: Watch: Miley Cyrus's Transformation from Disney Days to VMAs
"If you look at what I used to look like, my body, it's been humbling, and you look at the world differently," she says. "Things can change at any moment for any of us, and we have to rely on the kindness and patience of others, but more importantly we have to learn to be patient with ourselves and find that true meaning or purpose. I prefer to be positive."
Winsor believes stars flock to her studios because of the environment she has created there.
"My method of Pilates is not particularly congruous with exercises, as much as it is with attitude and support," she says. "I developed a method in which people would feel comfortable when they came into the studio, so that I could get the best results from them. Because after all, it's about them – it's not about me."
Winsor is passing on the torch and her teachings to her senior trainer Saul Choza, who will open a Winsor Pilates studio in West Hollywood later this month.
"If it ever comes to a point where I can't teach anymore – which I highly doubt – Saul will carry that on for me."