Former Yahoo CEO Carol Bartz has some advice for current CEO Marissa Mayer: Change is harder than you think. "One piece of advice I would give her is changing culture is not a sprint, it’s a marathon," Bartz said at Fortune’s Most Powerful Women summit, reports The New York Times's Claire Cain Miller. "It’s very, very hard to affect culture. And you can get surprised thinking you’re farther down the path of change than you really are because, frankly, most of us like the way things are," she said. Since taking the helm in July, Mayer has been all about "culture change," starting with free food, swag, hipper work spaces, and new iPhones, and lately, talking up broader corporate strategy changes as well. In a recent company meeting, for example, Mayer mentioned getting away from "one person consensus" culture, reported AllThingsD's Kara Swisher. 

Bartz, however, may not be someone Mayer wants to take advice from, as she left Yahoo on bad terms, claiming "these people [the board] fucked me over," to use her words. She claims she did everything the board asked, and still got fired. That in and of itself may be another lesson the current CEO can learn from her predecessor. One of Bartz's regrets, according to Miller, was not having a better relationship with the board that ended up firing her. "I didn’t understand or have the time or take the time—that’s a much better thing to say, take the time—to understand the relationships they had between themselves," she said. Mayer might want to listen to that bit of musing, as her fate ultimately lies with them. 

Since her hiring, Mayer so far hasn't had any tiffs with the board, from what we can tell. That's to be expected, since they hand-picked her just a few months ago. What could have gone wrong? Business Insider's Nicholas Carlson did say that "Yahoo's board kind of screwed" her over last month, when it decided to give billions of dollars to shareholders instead of reinvesting in the company. Apparently, Mayer was okay with this. In any case, she may want to consider her predecessor's wisdom if she wants, say, more engineers in the future.