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Lamar Odom has voluntarily checked himself into rehab, more than a year after he was found unconscious at a brothel in Crystal, Nevada. The retired pro basketball player is seeking treatment at a rehabilitation center in San Diego, California, a source tells E! News.

"It was his own decision. He wanted to work on his mental and physical health for the next chapter of his life," the source says. "He has not fallen off the wagon, but he understands the importance of maintaining his sobriety."

An insider confirms to PEOPLE that the former NBA star is seeking treatment at the facility as "a precautionary measure." The insider says, "Lamar checked into rehab a week ago. He plans to stay for 30 days. It's a substance abuse program, but he was not abusing drugs when he went in. He is clean. This is a precautionary measure."

"He wants to stay clear and focused. With the divorce from Khloe being finalized and the holidays coming up, he doesn't want to slip up. He's trying to take care of himself. He really wants to be better," the insider adds. "His friends and family encouraged him to go in and he agreed and made the decision."

The news comes just days after a judge finalized his divorce from Khloe Kardashian. According to court documents, Lamar and Khloe's marriage will be legally terminated on Saturday.

Khloe previously called off their divorce following Lamar's near fatal overdose in October 2015. She and his family reportedly staged a surprise intervention in July this year after he was kicked out of a Delta flight for being "very drunk" and vomiting on the plane, but he allegedly refused to seek treatment.