CHARLOTTE, N.C. (AP) — Dale Earnhardt Jr. abruptly announced his retirement at the end of the season Tuesday, a decision that will cost NASCAR its most popular driver as the series scrambles to rebuild its fan base.

Colorful, candid and talented, Earnhardt has been plagued by concussions the last several years and he missed half of last season recovering from the latest head injury. It caused him to delay contract talks on an extension to drive the No. 88 Chevrolet, and the two-time Daytona 500 winner with deep family roots in auto racing appears ready to call it quits.

A third-generation racer, Earnhardt turns 43 in October, is newly married and has said he wants to start a family.

His wife, Amy, posted on Twitter shortly after the announcement: “I’m so proud of Dale for working so hard to get back and even prouder for his courage & self awareness to make the decision to retire. I’m sure God has many other great plans for him and us!”

Earnhardt has become a vocal advocate for research of sports-related brain injuries, and the hit he took last June led to months of rehabilitation that gave him a new perspective on his life. The concussions left him with nausea, double vision, anxiety and a multitude of other symptoms that he’s discussed in great detail.

Earnhardt is not off to the greatest start this season, with only one top-five finish so far. He took another hit Monday at Bristol Motor Speedway when a mechanical issue caused him to crash.

In a typical Earnhardt move, a fan tried to take a selfie with Earnhardt as the driver made his way to the care center for the mandatory checkup after his hit. Although the fan was pushed away at the time, Earnhardt found him after his stop in the care center and later posted on Twitter the fan got his picture.

He did not seem fazed by Monday’s crash.

“I feel good. We’ll get in here and find out,” he said as he walked to the care center.

Earnhardt set an afternoon news conference with team owner Rick Hendrick to discuss his decision. Hendrick Motorsports said in a news release that Earnhardt informed his team of his decision early Tuesday. Hendrick Motorsports said Earnhardt first discussed retirement with his boss on March 29.

Earnhardt has won NASCAR’s most popular driver award a record 14 times. He has 26 career Cup victories and is a two-time champion of NASCAR’s second-tier series. But the son of the late seven-time champion has never won a Cup title.

Earnhardt has driven for Hendrick since 2008 after a nasty split with Dale Earnhardt Inc., the team founded by his father but run by his stepmother. He was unhappy with the direction of DEI since his father’s 2001 death in a last-lap accident at the Daytona 500, and a frosty relationship with his stepmother led him to bolt to NASCAR’s most powerful team.

Earnhardt made his first career Cup Series start on May 30, 1999, at Charlotte Motor Speedway. The Kannapolis native is in his 18th full-time season at the Cup level and he made his 600th career series start earlier this year at California.

His retirement is just the latest in a series of veterans stepping away from the sport after long and popular careers.

Jeff Gordon called it quits after the 2015 season, but he was a fill-in last year as Earnhardt recovered. Tony Stewart retired at the end of last year.

Now Earnhardt, the last of the true country boys, is following their exit. Born and raised in North Carolina, Earnhardt has deep roots in NASCAR. His Hall of Fame father Dale won seven titles and, known as “The Intimidator,” was one of the greatest drivers in NASCAR history.

Earnhardt’s grandfather, Ralph, ran 51 races at NASCAR’s highest level.

“Dale Jr. has had a huge impact on our sport – and you can see that every week with his legion of fans and Junior Nation,” Gordon said in a statement released by Fox Sports, where he now works as an analyst. “He has a tremendous sense of the history of NASCAR and, while he shares his father’s name, Dale has made a name for himself with his accomplishments in racing. While we will miss Dale on the track next year, he loves this sport, those working in the industry and the fans too much to ever be too far away.”

In this Feb. 20, 2016, file photo, Dale Earnhardt Jr looks from the garage before practice at Daytona International Speedway in Daytona Beach, Fla. Hendrick Motorsports says Dale Earnhardt Jr. will retire at the end of this season. (AP Photo/Wilfredo Lee, File)