"I was in the gym, and the most excruciating pain, like an elastic band just went like snap in my head and an enormous amount of pressure suddenly," she recalled of her first hemorrhage back in 2011. "And then very, very, very quickly I realized I couldn't stand and I couldn't walk. And in that moment, I knew I was being brain-damaged."
Despite the serious nature of the injury, Clarke returned to work just six weeks after the hemorrhage.
"It's like, 'Hey, thanks for giving me the job. Super appreciate it. I just had a little thing. It's fine. I'm fine,' and so I was pretty much fine," she said.
The second hemorrhage came two years later and was much more serious than the first.
"So, the second one, there was a bit of my brain that actually died," Clarke explained, as photos of her in the hospital flashed on the screen. "If a part of your brain doesn't get blood to it for a minute, it will just no longer work. It's like you short circuit. So, I had that."
The doctors were unsure about which specific part of her brain died, but thought it may be related to her concentration or peripheral vision.
"I always say it's my taste in men that's no longer there! That's the part of my brain, yeah, my decent taste in men," she quipped, before revealing that she feared her ability to act was actually the area of her brain that was affected.
"That was a deep paranoia, from the first one as well," she admitted. "I was like, 'What if something has short-circuited in my brain and I can't act anymore?' I mean, literally it's been my reason for living for a very long time."
Her recovery was very much "a day-to-day thing," one where Clarke said she "definitely went through a period of being down." But, it was her role as Daenerys Targaryen in Game of Thrones that really helped her through the trying time.
"You go on set and you play a bada** and you walk through fire, and that became the thing that just saved me from considering my own mortality," she said.
The interview came just days after Clarke's appearance on The Late Show With Stephen Colbert, where she opened up about how her perspective on life has changed since her health scares.
"Being completely honest it made me petrified most of the time, which happens a bunch," she said. "I wish I could sit here and say I was just like, 'Let's go, I don't know, jump out of a plane,' [but] I really wasn't."
"... At some point you start to realize how lucky you are... The perspective that that gives you is enormous. And then that is, for the rest of your life, you're lucky," she added. "You can know how lucky you are."
When ET's Leanne Aguilera caught up with her Game of Thrones co-stars, Iain Glen and Jason Momoa, they praised Clarke for her strength.
"I've kind of been a part of that whole situation for a very long time, so we've had so many scares and trying to find the right way to come out and help," Momoa said. "I just think it's beautiful that... she's so brave in helping the world and trying to raise awareness."
"I'm very sad, because we almost lost her the first time. So, I love her to bits and she's here and she's going to do great things with it and teach the world," he added.
"She's such an amazing lady, and she was so strong, but she had real scares," Glen agreed. "I think when you sort of come out the end of something like that, everything must feel golden. I think the Thrones family were great with her. I hope she'd say that, but they shepherded her and looked after her as much as they could."
"I think in a funny way, she was always happy to get back to... the warm world of Thrones as that contradiction [to time in the hospital]," Glen added. "But the spirit has always been extraordinary for all of us as actors while we've been on the show."
The eighth and finale season of Game of Thrones premieres April 14 on HBO. Watch the video below for more on Clarke: