(CNN) -- Brittany Maynard, the 29-year-old who said she had terminal brain cancer and would take medication to end her life under Oregon's "Death with Dignity Act," has died, advocacy group Compassion & Choices said in a Facebook post Sunday.
"Brittany chose to make a well thought out and informed choice to Die With Dignity in the face of such a terrible, painful, and incurable illness," a post on her website said. "She moved to Oregon to pass away in a little yellow house she picked out in the beautiful city of Portland."
In its Facebook post, Compassion & Choices, an end-of-life choice advocacy group that has been working closely with Maynard, said she "passed peacefully in her bed surrounded by close family and loved ones."
The post contained a final message from Maynard, who expressed a note of deep thanks to all of her supporters, whom she "sought out like water" during her life and illness.
"It is people who pause to appreciate life and give thanks who are happiest. If we change our thoughts, we change our world! Love and peace to you all," she said.
Maynard graduated from University of California, Berkeley, and earned a Masters in Education from University of California, Irvine, according to the post. She was a world traveler who volunteered at a local animal rescue organization before her diagnosis and lived 29 years of "generosity, compassion, education, travel, and humor," the post said.
Maynard is survived by her husband and his family, her mother and stepfather.
"While she had longed for children of her own, she left this world with zero regrets on time spent, places been, or people she loved in her 29 years," the post said.
Maynard's story spread rapidly on social media as a video explaining her choice garnered more than 9 million views on YouTube.
She became a prominent spokeswoman for the "death with dignity" movement, which advocates that terminally ill patients be allowed to receive medication that will let them die on their own terms. She also became a lightning rod for criticism from people who oppose that approach.
"I quickly decided that death with dignity was the best option for me and my family," Maynard wrote in an opinion column for CNN explaining her choice. "We had to uproot from California to Oregon, because Oregon is one of only five states where death with dignity is authorized."
In a video released last week, Maynard said she hadn't yet decided when she would end her life.
"I still feel good enough, and I still have enough joy, and I still laugh and smile with my family and friends enough that it doesn't seem like the right time right now. But it will come, because I feel myself getting sicker. It's happening each week," Maynard said in the video, which was produced by Compassion & Choices and released to CNN last Wednesday.
Maynard said she had stage IV glioblastoma multiforme, an aggressive form of terminal brain cancer.
When she first started speaking out about her decision, Maynard said that in early November she planned to take the medication she'd been prescribed. In her latest video, she said she was waiting to see how her symptoms progress before deciding on a date.
But taking too long to make that choice was one of her greatest fears, Maynard said.
"The worst thing that could happen to me is that I wait too long because I'm trying to seize each day," she says, "but I somehow have my autonomy taken away from me by my disease, because of the nature of my cancer."