Kathryn Hartmann was born in Mission, Texas, the oldest of four children. She attended Catholic school from 5th to 8th grade, and at the age of nine, her goal was to become a physical therapist for children.

She taught biology, chemistry, and physics to students from sixth grade through high school for many years. She then went on to complete a Master's of Science in Biology and taught at both public and Catholic schools. Years later, she was accepted into the PT program for a Master's in Physical Therapy. She began teaching at Northwest Vista and St. Phillips Colleges and later at Incarnate Word University's School of Physical Therapy.

In 2007, she went back to school again to complete a Doctorate in Physical Therapy at UTMB. She's been a physical therapist for over 20 years, working with infants in the NICU through patients aged 106 in nursing homes. Hartmann has a specialization in physical therapy for children ages 0 to 3 with an emphasis in neurology from UTMB Galveston. Dr. Hartmann has also served in Ghana, Africa, at a Catholic mission that helps children and adults with amputations and other injuries for rehabilitation.

Even after becoming a physical therapist, she continued to teach a variety of subjects. She joined Lumen Christi Academy in April 2024, teaching middle and upper school science courses.