SSG Marks began swimming in 2011 at the Brooke Army Medical Center in Fort Sam Houston. In April 2010, she sustained injuries to both hips while on assignment in Iraq as a combat medic for the U.S. Army. She underwent three operations to restructure her hips. An illness in 2012 caused a further reduction in mobility in her legs, and decreased her lung capacity leading to her experiencing disorientation and vision issues when she is swimming. She fell ill in September 2014 while travelling to the Invictus Games in London, which resulted in her being hospitalized and put on life support for 10 days. She woke up in the same hospital in Germany that she had been medically evacuated to from Iraq four years earlier. The illness resulted in a neurological impairment, decreased lung capacity, and a further reduction of mobility in her legs. She returned to training in December 2014. She is a member of the U.S. Army World Class Athlete Program (WCAP), which gives injured soldiers the opportunity to train full-time in competitive sports. In 2012 she became the first Paralympic swimmer to be chosen to join WCAP.  2016 Paralympic Champion - 100m Breaststroke, 2016 Paralympic Bronze Medalist - 4x100m relay.

Daughter of James and Andrea Marks.  Has one brother, Jacob, and two sisters, Maggie and Stephanie.  Father James, who also served, is her hero.  Recipient of the Pat Tillman Award at the 2016 ESPY Awards.  Has a cat named One-Eyed Willie.