Kurt Busch is retiring from NASCAR’s Cup Series.

The 45-year-old Busch held back tears as he announced his retirement Saturday at Daytona International Speedway.

Busch, the 2004 series champion and 2017 Daytona 500 winner, has been unable to shake the lingering effects of a concussiona year ago.

“My body is just having a battle with Father Time,” Busch said. “I’ve had arthritis ever since I can remember. My gout has flared up where I can barely walk in some days. Just pushing to get through physical therapy and continuing to work out.”

According to The Associated Press, Busch joins a short list of drivers in recent years whose bodies helped prompt decisions to walk away: Dale Earnhardt Jr. (concussions) and four-time champion Jeff Gordon (lower back). Busch said he was taking prerace shots last summer — before his concussion — “just so I could move my knee and move my feet.”

The Las Vegas native suffered a life-changing concussion during a qualifying crash at Pocono Raceway last summer. After slamming into the wall backwards, the front end of his Toyota smacked it at such a G-force that raised safety concerns about the Next Gen cars.

Busch won 34 races in 776 starts over 23 years in the Cup Series. He landed as a consultant for his old 23XI Racing team and Toyota. He counseled Travis Pastrana at the Daytona 500 in February and has thrown his arms around anyone in the garage who needs advice.

The Associated Press contributed to this report.