Jon Gosselin on Where He Stands With Ex Kate and When He Plans to Marry Girlfriend Stephanie Lebo (Exclusive)

Plus, are wedding bells in the future for Jon and girlfriend Stephanie Lebo?

Jon Gosselin is looking to make some major changes in his life.

ET's Kevin Frazier sat down with the reality dad-turned-DJ this week at the Beverly Hills Rejuvenation Center in Los Angeles, where the father of eight and daughter Hannah were both undergoing ultrasound therapy for weight loss from wellness expert Dan Holtz.

Jon explained that he became interested in the treatment after becoming "complacent" with his health.

"I'm in a great relationship with my girlfriend, Stephanie [Lebo], just, as a DJ, I work [from] 10 p.m. to 2 a.m., I work Thursday, Friday, Saturday, Sunday," he noted. "It's the nighttime lifestyle -- and I just kind of, like, gained weight. It just kind of happened."

Plus, Jon shared, "Heart disease runs in my family. My dad had congestive heart failure. He died almost 18 years ago... He died at 62, and his father died at 65, so I keep track of that kind of stuff."

Jon admitted that he's been wary in the past about popular fad diets and weight loss trends, but said the combination of seeing girlfriend Stephanie have success with Ozempic and meeting Holtz at Sundace and hearing about his therapies, he was willing to give it a shot in order to improve his health and gain some confidence in his chosen field.

"Vegas, Miami... I go to places where I am twice as big as everyone," he said of life as a traveling DJ, motioning to the jacket he wore for his ET interview. "This is the first time I had to buy XL! And XL doesn't really fit me, because I'm short. I'm 5'8... the sleeves are too long. Like, you got to have tailored clothing. Why should I even go through that, when I could just change my lifestyle?"

So, after making some changes that will hopefully help him reach his goal weight, could Jon see himself walking down the aisle once again?

"I love Stephanie and I have future plans with her, but I want to be in maybe the best shape of my life," he shared. "She loves me for who I am, dad bod or whatever, but in my mind, you know, we all see ourselves as 25 and fit... that's where I wanna be."

"I have plans," he added of what his future with Stephanie could look like. "We have a house together... but I want to get this figured out, my health."

Jon admitted that since this would be Stephanie's first wedding, she'll likely be the one who will get to plan her dream day. However, before any of that can happen, he needs to pop the question.

"I didn't even propose yet, so we got to figure that out," he noted with a laugh, though he assured, "It's coming, yeah."

And how does his ex-wife, Kate Gosselin, feel about Jon potentially bringing Stephanie into the fold amid their contentious co-parenting -- which recently saw Kate lose a child support court battle against her ex?

"Kate doesn't care what I do," Jon said shortly. "Kate does what Kate does. Kate only cares about Kate."

He added that he doesn't allow his ex to inform any of his present-day decision-making.

"It's not a problem anymore, I guess," he continued. "I don't know. I really don't know, because I don't talk to her."

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