You know what her bottom line is? Suck it up—just make yourself exercise.

Fleshner is very clear: It's not like you find your dopamine jackpot and your brain immediately says, "Now we exercise every day." For a while, you still have to force yourself to do it. But, I tell her, I have a very good reason not to: I know her research found that in animals, forced exercise doesn't lead to the same physiologic benefits that voluntary exercise does. In fact, it actually weakens the animals' immune systems by causing an increase in stress hormones in the body. I ask her about this, and she says it's true, but I don't have to worry about that. Why? Because I won't have to make myself exercise long enough to cause problems. To which I say, "Excuse me?"

Then she tells me something wonderful: All I have to do is force myself to exercise regularly for about two weeks, maybe three, and my brain will start producing a protein called brain-derived neurotrophic factor (BDNF), which she calls Miracle-Gro for the brain. It increases brain plasticity, so you can think clearly and focus for longer periods of time. It also increases dopamine neurotransmission, which means the more I exercise, the more reward I get, and the more my dopamine system is activated to make exercising a habit I'll soon crave.

"Just put on your Rollerblades," Fleshner tells me. "Strap on some headphones, leash up your dog, go outside, and start exercising right now."

Long, silent pause.

"I'm serious," she says.

I sit there holding the phone for a second before thinking, "Oh, what the hell. Three weeks isn't that bad." So I head out for day one. And yes, it's day one again, because I didn't go out for day two last time, which means I'm starting from scratch.

When I began this quest to find out why it's so hard to change unhealthy behaviors, I talked with more than a dozen scientists. Each one laughed and said some version of this: "If I could answer that question, I'd win a Nobel Prize and have drug companies lining up at my door for miles."

But the truth is, scientists have uncovered some very important things. To begin with, change is monumentally difficult. Some people can just wake up one morning, decide to change, and stick with it. But many, perhaps most, can't. The reason may be genetic; it may be the way you were raised; perhaps some people have stronger frontal lobes than others. Scientists still aren't sure. What they do know is, if you're one of those people who struggle, that's nothing to beat yourself up over—it's just the way your brain works. But it's also not an excuse to toss in the towel and say, "Well, I don't have enough dopamine" or "My bad pathways are too strong." As Bruce Wexler told me, "The more we understand what we're up against, the more we can develop strategies that will help us work with our brains to change successfully."

So instead of waking up New Year's morning and saying, "I'm going to do X now," then berating yourself a month later when that resolution didn't work, remember: You're doing nothing less than rewiring your brain. Approach change as if you're learning a new language or a new instrument. Obviously, you're not going to be fluent or play symphonies instantly; you'll need constant focus and practice. Overcoming an unhealthy habit involves changing the behaviors associated with it and managing stress, because stressing about change (or anything else) will knock you off the wagon faster than you realize. Above all, get that dopamine system going: Find rewards—make them instant, and don't be stingy. Your brain needs them. And I promise (well, Volkow, Schlund, Wexler, and Fleshner promise) it gets easier. That's not a bunch of self-help nonsense. It's biology.

Advice for a Better You


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