Cory Monteith (Finn) has entered rehab for a substance addiction, and his Glee co-stars have been quick to tweet their support of his decision. And yes, the choice to seek treatment was all Cory's. The star, who went to rehab once before over 10 years ago, voluntarily checked himself in. Plenty of fans have been vocal about their support of Cory's brave and responsible choice. We wish him well on his recovery!