Susan Wojcicki is stepping down as CEO at YouTube after spending nine years as the head of the social media platform.

In a blog post today, Wojcicki said that she was now going to spend time “ focused on my family, health, and personal projects I’m passionate about.”

Neal Mohan will become the new CEO.

Wojcicki said today that she would help with the CEO transition process, but that longer term, she would take on an advisory role across Google and Alphabet.

Wojcicki detailed how earlier in her career she joined Google, the owner of YouTube, when the search engine was being built by “a couple of Stanford graduate students,” Larry Page and Sergey Brin.

“I saw the potential of what they were building, which was incredibly exciting, and although the company had only a few users and no revenue, I decided to join the team,” she wrote. “It would be one of the best decisions of my life.”

Wojcicki went on to have various responsibilities, including managing marketing, co-creating Google Image Search, leading Google’s first Video and Book search, as well as early parts of AdSense’s creation, working on the YouTube and DoubleClick acquisitions, and serving as senior vice president of Ads. Google purchased YouTube in 2006.

Wojcicki said she’s worked with Mohan for nearly 15 years. He came over to Google during the DoubleClick acquisition in 2007 and later became senior vice president of Display and Video Ads. He became YouTube’s chief product officer in 2015.

“He has a wonderful sense for our product, our business, our creator and user communities, and our employees. Neal will be a terrific leader for YouTube,” Wojcicki said.