Uh-oh, the new year's just begun and already you're finding it hard to keep those resolutions to junk the junk food, get off the couch or kick smoking. There's a biological reason a lot of our bad habits are so hard to break – they get wired into our brains.

噢喔，新的一年才刚刚开始，你就发现很难坚持“告别垃圾食品、远离沙发、戒烟”这些新年决心了吧？我们很难改掉坏习惯是由于生物学的原因——这些坏习惯根植于我们的大脑中。

That's not an excuse to give up. Understanding how unhealthy behaviors become ingrained（根深蒂固的） has scientists learning some tricks that may help good habits replace the bad.

"Why are bad habits stronger? You're fighting against the power of an immediate¹ reward," says Dr. Nora Volkow, director of the National Institute on Drug Abuse and an authority on the brain's pleasure pathway.

"We all as creatures are hard-wired that way, to give greater value to an immediate reward as opposed to something that's delayed," Volkow says.

Just how that bit of happiness turns into a habit involves a pleasure-sensing chemical named dopamine（多巴胺） . It conditions the brain to want that reward again and again – reinforcing the connection each time – especially when it gets the right cue from your environment.

People tend to overestimate² their ability to resist temptations around them, thus undermining attempts to shed bad habits, says experimental psychologist Loran Nordgren, an assistant professor at Northwestern University's Kellogg School of Management.

Even scientists who recognize it can fall prey³.

"I don't like popcorn⁴. But every time I go to the cinema, I have to eat it," Volkow says. "It's fascinating."

A movement to pay people for behavior changes may exploit that connection, as some companies offer employees outright⁵（完全的，彻底的） payments or insurance rebates⁶（回扣） for adopting better habits.

However paying for behavior plays out, researchers say there are some steps that may help counter your brain's hold on bad habits:

Repeat, repeat, repeat the new behavior – the same routine at the same time of day. Resolved to exercise? Doing it at the same time of the morning, rather than fitting it in haphazardly⁷（偶然地） , makes the striatum（纹状体） recognize the habit so eventually, "if you don't do it, you feel awful," says Volkow the neuroscientist, who's also a passionate⁸ runner.

Exercise itself raises dopamine levels, so eventually your brain will get a feel-good hit even if your muscles protest.

Reward yourself with something you really desire, Volkow stresses. You exercised all week? Stuck to your diet? Buy a book, a great pair of jeans, or try a fancy restaurant - safer perhaps than a box of cookies because the price inhibits⁹ the quantity.