Formula One champion Nico Rosberg stunningly retired from racing on Friday, five days after claiming his first world championship.
Rosberg said he made the decision on Monday, a day after finishing second at the season-ending Abu Dhabi Grand Prix to clinch the F1 title.
"I am on the peak, so this feels right," Rosberg wrote on Facebook.
He also of the difficulties he faced over a season that took a toll on people close to him: "It was a whole family effort of sacrifice, putting everything behind our target."
His Mercedes team said on its website that the 31-year-old German driver "will stop racing in Formula One with immediate effect."
Rosberg said it had been his dream, "my 'one thing' to become Formula One world champion. Through the hard work, the pain, the sacrifices, this has been my target. And now I've made it. I have climbed my mountain."
Rosberg, who won 23 races and 30 pole positions, said he began thinking of retirement after winning in Suzuka in early October, "when the destiny of the title was in my own hands."
Mercedes chief Toto Wolff paid tribute to Rosberg for making a "brave decision."
"He has chosen to leave at the pinnacle of his career, as world champion, having achieved his childhood dream," Wolff said. "The clarity of his judgment meant I accepted his decision straight away when he told me."