"This past Monday marked three weeks since I was discharged from the hospital, and I have been slowly getting better every couple of days," he said.
Rosenbaum said he's been doing physical and occupational therapy to help him regain muscle strength.
"I'm progressing," he said.
"My physical therapist said that I'm very, very lucky that I'm able to do things three weeks later that I shouldn't be able to do, which is all incredible. My fine motor skills are virtually all back."
Rosenbaum went public with his diagnosis on Instagram in December, describing Guillain-Barre syndrome as "a very surreal, and humbling, and crazy, rare" disorder.
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The disease causes a person's immune system to damage the nerves.
"Just can't really believe it," Rosenbaum said.
Rosenbaum spent the holidays with his wife, "The Bachelorette" Season 7 star Ashley Hebert, their two children, son Fordham and daughter Essex, and Hebert's parents.
He shared a photo with Hebert in the snow last week.
"My real snow angel," Rosenbaum captioned the post.
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