Former middleweight titleholder Daniel Jacobs on Saturday announced his retirement from boxing.

Jacobs, 37, ended a nearly two and a half year boxing hiatus earlier this month, but he lost a unanimous decision to Shane Mosley Jr. in his return in Anaheim, California.

Jacobs, of Brooklyn, New York, retired with a record of 37-5 (30 KOs), including a 2018 win over Sergiy Derevyanchenko to win a world middleweight title and a 2014 victory over Jarrod Fletcher to win a secondary middleweight belt, which Jacobs successfully defended four times.

“Announcing my retirement,” Jacobs posted in a message on his Instagram account. “I want to show my gratitude and appreciation to the sport of boxing as it has changed my life in ways I never could imagine it has instilled so many morals and values I wouldn’t have learned otherwise. Boxing made me the man I am today.”

At least as instrumental as boxing in outlining the narrative of Jacobs’ story was his terrifying 2011 battle with bone cancer, which derailed his career and threatened his life – but ultimately led to his moniker, “The Miracle Man,” after he not only survived but also went on to become a world titleholder.

“It has always been my dream to be a champion in life and when boxing found me, I was a poor kid growing up in Brownsville Brooklyn with not much to look forward to,” Jacobs wrote in his social media post. “As a young black kid I was being forced fed an identity that I wasn’t important or wouldn’t succumb to anything substantial in life I was told the ghetto that I grew up in was was full of criminals with no future and I will be a statistic just like my peers and the ones that came B4 me dead or in jail with no potential to make it out or to make a success of myself.”

In his social media post, Jacobs thanked his fans, schoolteachers, friends, boxing mentors and community, and his son Nathaniel for their support, guidance and motivation.

“Through the ups and downs inside & out of the ring, I have manage to become 2x world champion and I’m able to say I’m the first cancer Survivor to be a boxing world champion the biggest accomplishment I’ve ever could achieve,” he wrote. “Being able to inspire others with my story has always made me feel like my life meant more than just fighting inside the ring.”