Jon Gosselin chats with ET's Brice Sander at the West Hollywood Beverly Hills Rejuvenation Center grand opening. The reality star reacts to his sextuplets turning 21 next year and shares how they plan to celebrate. Jon also opens up about his health and fitness journey and gives an update on his future with girlfriend Stephanie Lebo. Plus, he shares whether he'd return to reality TV and if he's ever rewatched 'Jon & Kate Plus 8.'