Just over a year after Odom's health scare, a source tells ET that he has checked himself into rehab
. "It was his decision to go back," the source says of the 37-year-old athlete. "He wants to get better and recently realized he needs to do this for himself, and especially for his children. He knows he needs help and unfortunately, this is something he'll need to take care of for the rest of his life. Drug and substance abuse is a serious issue."