WATCH: How Nate Boyer convinced Colin Kaepernick to kneel rather than sit for the national anthem

San Francisco 49ers quarterback Colin Kaepernick continues to stir controversy across the country by refusing to stand for the national anthem, but his protest has been impacted in an important way by former Texas Longhorns long snapper Nate Boyer.

In this clip from HBO’s Real Sports with Bryant Gumbel, Boyer explains how he convinced Kaepernick to kneel rather than sit during the anthem:

“I showed [Kaepernick] a text message from a good friend of mine who is still in the special forces,” says Boyer, a former Seattle Seahawk and United States Army Green Beret. “[The text message] said, ‘Nate, I’m standing on the tarmac,’ as a plane came back from Afghanistan to drop off a coffin that was draped in an American flag for one of our brothers.

“I just couldn’t stop looking at staff sergeant Thompson’s wife and seeing the grief and the pain. I got filled with rage for anybody that disrespects what we are fighting for, and what we stand for. I showed Colin that text. At that moment, I saw in his eyes — it really affected him emotionally.

“It had a big impact on his next words, which were, ‘I want to do something different.’ We sort of came to a middle ground where he would take a knee alongside his teammates. Soldiers take a knee in front of a fallen brother’s grave to show respect. He said, ‘I think that would be really powerful.’ He asked me to do it with him. I said, ‘Look, I’ll stand next to you. I’ve got to stand though, I’ve got to stand with my hand on my heart. That’s just what I do and where I’m from.’”

Boyer wrote an open letter to Kaepernick last month, sharing his own experience with the national anthem after everything he had been through in his life.