Ashton Kutcher addressed his health, three years after suffering from a rare form of vasculitis. The 44-year-old actor tweeted on Monday night, hours after his discussion with Bear Grylls about his struggle with the disease made headlines:

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Kutcher broke news of the rare autoimmune disorder diagnosis during a sneak peek of his “Running Wild with Bear Grylls: The Challenge” appearance: “I had this weird, super rare form of vasculitis, that, like, knocked out my vision, it knocked out my hearing, it knocked out, like, all my equilibrium,” Us Weekly reported.

He continued, “You don’t really appreciate it until it’s gone. Until you go, ‘I don’t know if I’m ever going to be able to see again, I don’t know if I’m ever going to be able to hear again, I don’t know if I’m ever going to be able to walk again.’”

Kutcher told Bear Grylls that he’s “lucky to be alive,” adding: “The minute you start seeing your obstacles as things that are made for you, to give you what you need, then life starts to get fun, right?

“You start surfing on top of your problems instead of living underneath them.”

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Grylls insisted, “What do they say in survival? Storms make you stronger. And I think he’s living proof of that.”

Kutcher, who shares daughter Wyatt, 7, and son Dimitri, 5, with wife Mila Kunis, also got pranked by Grylls during the episode, as the tables were turned following his “Punk’d” days.