Retired Texas Marine Staff Sgt. Jose Sanchez is a recovering amputee, but that didn't stop him from leaving an indelible mark on this year's Boston Marathon.

Sanchez was injured in 2011 while serving in Afghanistan and has been private about the incident until now.

Pretty amazing. #bostonmarathon #inspiring A post shared by Laura Vitalini (@lkv117) on Apr 17, 2017 at 8:41am PDT

For five years, a gift Sanchez received from his fellow Marines remained unopened. Yet, it was that gift that changed his perspective and spurred him from his antisocial state.

The gift was a large American flag signed by his fellow troops with notes of encouragement and inspiration.

Sanchez was determined to not merely put the flag away, but to display it in honor of the troops who motivated him to get past his anger and depression and find a positive outlet to give back. So he proudly displayed the flag as he ran the Boston Marathon.

"It's for others to be inspired, to be motivated. I don't do it for myself," Sanchez told WBZ. "We live for others — I've learned that throughout being angry, and frustrated, and with all that PTSD. I'm channeling it to be positive and to give back to whatever I have taken away from the community."

Sanchez completed the 26.2-mile race in just under six hours to benefit Semper Fi Fund, a charity that provides assistance to wounded service members and their families.