The perfect time for new habits, says Wharton behavior expert: It's 'the granddaddy of all fresh starts'

A perfect time for goal-setting and habit-building really does exist. Several of them do, actually.

That's according to Katy Milkman, a behavioral scientist at The Wharton School of the University of Pennsylvania, who calls them "fresh starts" — holidays or dates that signify the beginning of a new period in time.

The first day of any new month counts. So do Mondays, Labor Day, the Fourth of July and of course, the "granddaddy of all fresh starts," New Year's.

"We think about time like we are characters in a book living through chapters," Milkman tells CNBC Make It. "When we have these chapter breaks, it gives us a sense of disconnect from who we were in the last chapter, and we think, 'Oh, that was the old me, this is the new me.'"

That sense of disconnect matters: Motivation alone isn't enough to help you accomplish most goals, says Milkman, who has studied the concept of habit change for nearly 20 years. That's why "hacks" like visualizing your goals or repeating mantras aren't always as helpful as you'd hope.

But a little timing boost can help push you over the top, because a fresh start gives you a chance to step back and diagnose the reasons your habits aren't sticking, she says.

Here are two of the most common barriers people face, says Milkman — and how to do something about them during your next "fresh start."

When humans try to build new habits, they often jump into them as quickly as possible. People who decide to exercise more might go directly from their couch to rigorous, calorie-burning workouts.

That's unsustainable, says Milkman. If this sounds familiar to you, she has some advice: Make the process itself fun, rather than focusing on the outcome.

Milkman suggests a technique called "temptation bundling," where you combine "a chore with a temptation, and only let yourself enjoy that temptation while you're engaging in the chore," she says.

You might only allow yourself to watch your favorite television show while you're on the elliptical machine, for example. "Now, you start going to the gym at the end of a long day instead of dreading it," says Milkman. "And time flies while you are there."

You could find other ways to make the process fun, too — like involving your friends.

"Even if it is slightly less efficient, you should do the fun thing just to make sure you keep going," Milkman says. "Most goals require repeated effort, and if we don't enjoy it, then the instant gratification-craving part of us is like, 'Yeah, I quit.'"

Sometimes, when you try to create a new habit, life gets in the way. You say you'll work out a few times per week, but as you're leaving work, you realize you need to pick up your kids, or you made plans to hang out with a friend, or something else comes up at the last minute.

Or, you simply forget: Your brain goes on autopilot when you leave the office, and you arrive home only to realize that you were supposed to go the gym, and now you're out of time.

To combat both scenarios, cut your goals down into "bite-sized, approachable chunks," Milkman says. If you want to volunteer more, change that into something smaller and more concrete like, "I'm going to volunteer three hours a week."

Then, put that bite-sized goal into a detailed plan, she says. Specify exactly when those three hours per week will be: "I will volunteer for an hour at 6 p.m., right after work, on Mondays, Wednesdays, and Thursdays."

By making your plan as specific as possible, you force yourself to account for everything else you'll need to do that day — from buying groceries to making it home in time to shower and prepare dinner. You also create a pathway in your brain: The act of leaving work and the concept of 6 p.m. become mental cues that remind you of volunteering.

Once you've made an explicit commitment, you're more likely to actually do it — even if the agreement is just with yourself. Just asking people to make concrete voting plans ahead of an election can increase turnout, found a 2011 study from researchers at Harvard University and the University of Notre Dame.

"There is lots of research showing that this works," says Milkman.

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