A happiness expert shares her daily routine for success

Gretchen Rubin describes herself as an "extreme" person.

That's not to say she's a fan of windsurfing or spicy food or loud concerts. In fact, she dislikes most of those things.

Rubin, author of "The Happiness Project" and "Better Than Before: Mastering the Habits of Our Everyday Lives," considers herself extreme in her ability to develop and maintain habits.

While some people would find it boring to eat a similar low-carb lunch day after day, Rubin embraces the predictability.

"I feel like habits are freeing," she says.

As Rubin explains in the book, habits eliminate the need for decision-making. For example, you probably don't argue with yourself about brushing your teeth when you wake up - the behavior is automatic.

But Rubin says that people have different tolerances for routine, depending in part on their personalities. To that end, the book divides people into four types: Upholders, Obligers, Questioners, and Rebels.

Upholders respond readily to both inner and outer expectations; Questioners respond only to expectations that make sense to them; Obligers meet mostly outer expectations; and Rebels resist all expectations.

Rubin considers herself an Upholder. Because Upholders are naturally drawn toward rules and schedules, it's relatively easy for them to start new habits and stick to them.

"A highly, highly regimented life would be a dream [for me]," says Rubin, noting that family members have described her as a "monk."

Unfortunately, the demands of her current schedule make it impossible for her to do the exact same thing at the same time every day.

But Rubin does what she can to impose order on her days: She consistently sets her alarm for 6 a.m., even on weekends, and spends the first hour of her day checking email and social media. Most days include a yoga class or strength-training session that always take place at the same time.

Even her eating habits reflect the kind of rigidity that would drive some people crazy. Rubin maintains a low-carb diet that barely includes sugar or flour, and in the book she mentions that she eats pretty much the same foods every day.

On the flip side, Rebels often struggle with routine. "They quickly feel constrained and trapped by a habit atmosphere," Rubin says, adding that, "if it's on the schedule, it makes them not want to do it."

Ultimately, Rubin suggests that being healthy and happy isn't about changing your personality - it's about learning to work with it. That may mean following a strict daily routine, from a 6 a.m. meditation practice to a 10 p.m. journaling session. Or it could mean living each day completely differently, working from 9 a.m. to 5 p.m. on Monday and then working from 5 p.m. until midnight on Tuesday.

What all successful people share, Rubin says, is that "they've figured out how to do their own best work."