Willie Nelson is always on our minds, but especially this week, because he’s celebrating his 81st birthday. And also because on Monday, the legendary singer received his fifth-degree black belt in GongKwon Yusul, a martial art which he’s been practicing for 20 years.

“It’s just good for you physically. For your lungs. The more you’re breathing, exercising, the better you’re going to feel,” Nelson told Austin’s KVUE.

Shortly before the ceremony, the singer told the Associated Press that he was surprised to be receiving the degree at all. “I don’t know what else is out there,” he said. “I never thought about anything beyond second-degree black belt.”

Though Nelson is best known for his music (and for his prolific pot habit), it’s a bit lesser known that he’s very into martial arts too.

“I think martial arts is one of the best exercises you can do. Mentally, spiritually, physically, everything,” he told the AP.

This past weekend, Nelson was also inducted into the Austin City Limits Hall of Fame, so he’s had a pretty good week.

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