Known as Myrtilee as a child, she had long suffered from tuberculosis, and was not expected to live very long.Myrtle Fillmore studied spiritual healing in 1886. She attended lectures by Dr. E. B. Weeks, a student of Christian Science. Her health improved by 1888, which she attributed to prayer.

The pair established Modern Thought meetings designed to be held Sunday afternoons after participants had attended church. The Fillmores did not set out to create a new denomination, but eventually did so, calling it (Unity Farm) -- now known as Unity. Unity with Religious Science, Divine Science are the largest of the New Thought organizations.

Myrtle did not produce nearly the output of writings that Charles did. Her major work is the collection, Healing Letters."

Myrtle Fillmore lived many decades longer than any of her doctors believed possible. Concerned that she might be seen as a cult figure to be worshipped, her burial place, though somewhere in Unity Village, remains secret to all but her family so that it could not become a shrine.

Neal Vahle has written a biography of Myrtle Fillmore titled Torch-Bearer to Light the Way."