Jack Osbourne's fiance Lisa Stelly is "making sure he's healthy."

The 26-year-old reality TV star announced he was diagnosed with Multiple Sclerosis in June, soon after he and Lisa welcomed their four-month-old daughter Pearl.

Lisa is concerned with Jack's welfare and is being extremely supportive of her love.

"Lisa makes sure he's healthy -- eating right and exercising," a friend told Us Weekly magazine. "They love staying active as a family."

Jack is reportedly remaining in positive spirits despite being afflicted with the degenerative neurological disease.

"He knew something was wrong for a while," another source explained.

"Everyone is sad, but he is being strong about it."

Despite adopting an upbeat mind-set about the condition, Jack has previously spoken of how the illness has impacted on his career.

"I had booked a job, right when I got diagnosed, and the company didn't think I could actually perform the job," he said on TV show The Talk, which features his mother Sharon as a co-host.

"Out of everything, that's what has really ticked me off the most because it's like, Don't tell me what I can and cannot do'. At no point did they call me. I was offended by it." (C) Cover Media