The following is adapted from Dorie Clark’s new book Entrepreneurial You.

We’d all like to succeed in our professional lives. But what does that really mean?

The media holds up Richard Branson and Elon Musk as icons of what we should all aim to accomplish – Found a company! Become a billionaire! Go to Mars!

But for many entrepreneurs and professionals, the real challenge is fighting back against other people’s expectations and learning to define success on our own terms.

Michael Bungay Stanier faced just that conundrum. He’s a Toronto-based entrepreneur who built a successful coaching practice. But he had a rather alarming realization. “At a certain point,” he recalls, “I came to this insight that I actually didn’t enjoy coaching that much.” He was interested in helping people change behavior, but “it was too lonely, too isolated, the energy wasn’t right.”

Even though he was finally making good money as a coach, he realized he needed to turn down that work in order to build a more sustainable business model that better suited his personality. Instead, he now runs a company that trains managers to coach their own employees, allowing him to scale his impact and interact with more people – work that he truly enjoys.

Similarly, Jayson Gaignard – whom I also profile in Entrepreneurial You – is the organizer of a popular and exclusive conference, Mastermind Talks. With the conference’s success, it seemed like a no-brainer to start an even more exclusive, high-end mastermind group. He decided to bring together a group of professionals for quarterly, three-day retreats that were, in Gaignard’s words, “really cool, once-in-a-lifetime experiences.” Each retreat began with an “experience” day that featured an interesting activity to facilitate group bonding—such as behind-the-scenes tours of Cirque du Soleil, Apple University on the Apple campus, and the Aria Casino.

Day two of each session was a mastermind day in which participants could share their business challenges and learn from each other, and day three was a learning day, in which Gaignard would bring in outside expert speakers. Especially given the elite price point ($25,000 per person, per year), what’s not to love?

But Gaignard found that, in contrast to his Mastermind Talks conference—which were tiring yet exhilarating for him—facilitating the retreats was merely exhausting. “It just didn’t light me up. It actually drained me,” he says. “I thought I’d enjoy it, but I realized I didn’t.” Despite hundreds of thousands of dollars in forgone revenue, he shut the program down after two years. Sometimes, to preserve your happiness, you have to say no to the money.

But saying no creates space for you to choose your own priorities, and attend to what’s most important for you.

Jenny Blake, author of Pivot, thinks about her business as a mix of priorities, both financial and personal. “At the end of the day, I love having space and quiet and time to travel and think and write,” she says. “I have goals to earn a million dollars a year. I just wonder, does it need to happen with twenty employees, or can I do something like that on my own?”

As she points out, you have to get clear on what’s important to you. “I’ve seen what people do to make seven figures,” she says, “and I don’t necessarily enjoy the same activities. So I’ve sort of taken the slower, more winding path that feels authentic to me . . . I leave every day around two or three to go to yoga; I don’t work all day. I read for an hour in the morning. These are things I love doing and I’d rather have a slower-building income and keep a really healthy, calm lifestyle as much as I can.”

Your priorities may also change – quite unexpectedly. That’s why developing flexibility in your career, including entrepreneurial side income streams, can pay off. Natalie Sisson built a blog and book called The Suitcase Entrepreneur, and had spent time in 69 countries. But her definition of freedom – which had originally been all about travel – changed in August 2015, when her father got sick, and she decided to move home to New Zealand to spend time with him.

“That was the time at which I realized this freedom business model that I’d built actually gave me freedom in a totally different way than I tend to think about,” she says, “which was to drop everything and come home to be with family. Had I still been in the corporate world, I wouldn’t have had the leave; I probably wouldn’t have had the time or the money to fly all the way home.”

For her, she said, it became about “freedom of choice, and decisions, and what you make and how you spend your time. It became extra important to me during that time.” Her father died that December.

When it comes to crafting the business and the career you want, it starts with getting clear on your priorities—not what you think you should be aiming for, but what actually matters most to you.

Chasing someone else’s vision of the good life will never ultimately be fulfilling.

But when you redefine success on your own terms, it’s finally possible to reach it.

Dorie Clark is the author of the new book Entrepreneurial You. Her past books include Reinventing You and Stand Out, which was named the #1 Leadership Book of 2015 by Inc. magazine. She teaches for Duke University’s Fuqua School of Business, and you can download her free Entrepreneurial You self-assessment workbook