Nick Collison is calling it a career. 

The 37-year-old forward announced his retirement after 15 years with in the NBA, 10 of which were spent with the Thunder.

"I started in cold gyms in small towns in Iowa and ended up playing in more than 1,000 games over 15 years in the best league in the world. I've had an incredible run. I'm proud of my career," Collison said, via ESPN. "But it's time to go. I'm retiring from competitive basketball."

Collison was drafted 12th overall in 2003 by the Seattle SuperSonics, who relocated to Oklahoma City.

"I've played with some incredible players, future Hall of Famers, and had the unique experience of spending my entire career with one franchise, but in two different cities," he said. 

Collison went on to detail how the move from Seattle to Oklahoma City was tough, but by the second season as the Thunder there were glimmers of hope. The team had Russell Westbrook and Kevin Durant. James Harden had just been drafted. And Serge Ibaka had arrived.

"I remember thinking, 'Are we good? I think we're good,'" Collison recalled.

Collison said he would miss playing, but now it's time to focus on being with family and friends.

“I’ve had the privilege of being one of the guys on a basketball team for a long time," he said. "I’ve loved the friendships and appreciated the camaraderie. There is nothing better than being on the road and going on a run in the fourth quarter to put a game away, then going out with all of the guys after. … I got to stay here a long time, but now it’s time to go.”