Seven-time Olympic medalist Dana Vollmer will compete a final time in this week's national championship. 

She announced her retirement Monday on Twitter. 

Vollmer, 31, appeared at three Olympic Games: 2004 in Athens, 2012 in London and 2016 in Rio de Janeiro. 

The Granbury native wrote in a letter published on ESPN about physical and emotional obstacles she faced as an elite swimmer. 

"This is not letting go of a dream, it's having the ambition to start a new one," Vollmer wrote.

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The Granbury High School graduate became the first mother to win an Olympic gold medal at the 2016 games. 

"Over the years, sport and life fully merged, and the dance between sport experience and life experience enriched me in ways that I appreciate daily," Vollmer wrote in the ESPN letter. "But days only have so many hours, and other parts of my life are asking for my time and attention."