Show off your passion for running marathons and your love of knowledge with this stylish black t-shirt. The shirt features a graphic design of runners competing in a marathon, complete with stars. Made from a comfortable fabric, this t-shirt is perfect for everyday wear or as a motivational piece during your runs. The bold text "THAT'S WHAT I DO I RUN MARATHONS AND I KNOW THINGS" makes a statement and sparks conversation. Whether you're a seasoned marathoner or just enjoy a casual jog, this shirt is a must-have addition to your wardrobe. Great for gifting or wearing to your next race!