AUSTIN (KXAN) — Running a marathon is no easy feat, but can you imagine running more than 40 miles a day for 20 days in a row? An Austin runner is doing just that as he started his "Run Across Texas" on Oct. 1. ”In October, there is one mission and that is to get across Texas,” ultra runner Matthew Johnson said just days before he set out on his run. Johnson will run from El Paso to Galveston, which is close to an 850-mile journey, he will run between 40 to 50 miles a day until he finishes. ”Forty miles a day gets us done in 21 days, 50 miles a day gets us done in 17,” Johnson said. How The Morning Jo’s run club avoids the Texas heat Johnson is a military veteran and he’s running to raise money for ValorFit, a nonprofit that offers support services for veterans by getting them involved in group fitness and gyms. ”For me, it was...with this platform and with all the eyes I have on me now, what can I do to utilize this for good and, for me, fitness changed my life,” Johnson said. Johnson is no stranger to long runs, but admits this will be one of his toughest feats yet. ”I am ready to see the impact this has,” Johnson said. “I am excited to see the people that come to run with me, the people that come to high-five me along the way.” Johnson’s team will follow along in a van and RV to monitor him. Click here to donate to his cause of follow along his journey.