Let's imagine for a moment you went to sleep in 2003 and didn't wake up for 10 long years. And let's imagine you fell asleep in front of the TV in 2003 watching an episode of MTV's "The Osbournes" -- one of the first celebrity-family reality series that would help spawn many, many, ugh, so many, copycats. Your last impression of Ozzy Osbourne's then-teenage son Jack would've been of a lazy, overweight, drug-addled smart-aleck.
Well, you would've been in for a surprise of heart-attack proportions had you awoken from your 10-year slumber last week and tuned in to watch Jack all grown up as a ballroom dancing dynamo on ABC's "Dancing with the Stars."
Jack Osbourne, now 28, has changed a lot in the past 10 years. Like, a lot, a lot. Gone is the overgrown mop of curly brown hair. Gone are the 65 pounds of teenage chubbiness. Gone are the drugs and alcohol in quantities that could fell a Clydesdale.
The Jack Osbourne of today is a successful TV and film producer and bona fide star of whatever reality TV show he happens to appear on. It was "Dancing with the Stars" this fall, and before that, "I'm a Celebrity, Get Me Out of Here! NOW!" and before that, his British TV hit show "Jack Osbourne: Adrenaline Junkie."
It was quite a gods-be-damned moment then, just as Osbourne's TV career was in full swing again, that he was diagnosed with multiple sclerosis. The 18 months since have required much soul-searching on Osbourne's part.
"I felt a level of defeat, to a degree," Osbourne told ABC News correspondent Dan Kloeffler. "It was just like, 'Oh, man, really?' After just having a baby, getting married, now I have to deal with this?'"
Osbourne received the diagnosis three weeks after his wife, Lisa, gave birth to their little girl, Pearl. At the time, Osbourne was experiencing optic neuritis, a common condition in people with multiple sclerosis that causes a temporary loss of vision.
"The ER doctor, first he thought it was a stroke because he saw a lesion in my brain," recalled Osbourne. "Then the neurologist came in and was like, ‘Actually, no, it's not.’” It wasn't a stroke. It was MS.
"Both not good news. It's like, 'You wanna get hit in the face with the left hand or the right hand?'"
Osbourne has now taken his gift for story-telling and his medical (mis)adventures to the Web, starting a multiple sclerosis awareness campaign on behalf of pharmaceutical company, Teva Neuroscience. The site, which went live a few days ago, is called www.youdontknowjackaboutms.com.
"I wanted to do this awareness campaign because I couldn't find the information that was digestible enough for me," said Osbourne. "I thought doing 'youdontknowjackaboutms' was an interesting way, because it's more of an observational documentary series, kind of from my perspective -- meeting people in my life who either are my caregivers, or my friends, family [or] doctors."
Osbourne's type of multiple sclerosis, known as relapsing-remitting MS (RRMS), afflicts about 85 percent of all people with MS. RRMS differs from progressive MS in that patients deal with bouts of the autoimmune disease more sporadically.
In starting an MS awareness campaign, Osbourne had to become an expert in describing the disease in layman's terms.
"Essentially your body attacks your nerve endings, and there's fatty tissue around the nerve called myelin. ... It's like the plastic coating over a wire," explains Osbourne. "But what the disease does, it breaks down that coating and exposes the real nerves and causes them to inflame and not function correctly."
Somehow, even with bouts of numbness in his legs and the distorting of his vision, Osbourne was able to wow a national audience week after week this fall with his sweet freestyle, waltz and salsa moves on "Dancing with the Stars." He and partner Cheryl Burke trained six hours a day.
"It's incredibly difficult," according to Osbourne. "But you train so much that it's doable. Like it's one of those things where if NASA sat you down for 40 hours a week for 14 weeks to teach you to fly a space shuttle, you'd probably be able to fly a space shuttle."
Well, with NASA's space shuttle business now defunct, we'll never know, will we?
In the meantime, some were very wrong to write off the 17-year-old version of Jack Osbourne, lolling, half-sober, in bed, and 45 minutes late for school. Today, he believes not even MS will get in his way.
"When I dive into something, I never half-ass it. If I'm gonna do something, I'm gonna do it to the best of my ability ... until it's finished."
ABC News' Brian Fudge contributed to this episode.