New Year’s resolutions fail so often because people make them for the wrong reason.

John Medina knows a lot about how people operate. He doesn’t make resolutions, but he does have some advice for anyone who wants to have a better life in 2009. Take care of your brain.

Medina, a developmental molecular biologist, is an affiliate professor at the University of Washington and the University of Puget Sound. I sought his opinion because I liked his 2008 book, Brain Rules.

Your brain didn’t evolve to do tax returns or read novels. It’s a survival organ, Medina said.

Modern life is hard on brains, which evolved to serve people who were active, who needed to deal with short-term stress, who were constantly learning and needed sleep to offload what they’d learned during the day.

Given how things are going right now, we talked a lot about stress, which can do bad things to the brain.

Not all stress is bad, Medina said, and not everyone reacts to it the same way, but what’s definitely harmful is the stress of not having control.

Stressed-out brains don’t learn well, don’t solve problems well, can’t remember as much, and don’t have as much executive control.

Executive control is the brain function that allows people to do complex tasks like design satellites and it’s what keeps us from punching the boss when he says something dumb.

You can do several things for your brain that will help your stress level, too.

•Exercise is huge for a brain designed for an active species. Aerobic exercise helps repair areas of the brain damaged by stress and improves thinking.

•Get enough sleep — whatever feels right for you. During most of your time asleep, your brain is furiously working, storing memories, solving problems.

•Take a nap. Your brain really wants one, and a NASA study showed a 34 percent increase in efficiency after a 20-minute snooze. Bosses ought to demand that workers nap. “Don’t do anything between 2 and 4,” Medina said.

And if you thought you were making up for being groggy by multi-tasking, forget it.

Your brain is always busy doing lots of tasks at the same time, controlling breathing, circulating blood, but what it can’t do is more than one thing that requires your conscious attention. It switches back and forth fast enough to make you think you’re multi-tasking, but the gaps are long enough for you to wreck your car while talking on the cell phone.

Every year people promise to change, but Medina says January resolutions tend to be a cultural thing; everyone is talking about resolutions and writing about them, so you make a list. Doesn’t work.

Use the New Year as a time to see how you are doing on year-round goals. Learn more about your brain at www.johnmedina.com, if you’re curious. One of the great gifts our brains give us is curiosity. If you want a resolution, here’s one:

“Ventilate the intellect,” Medina said. “Fill it with things that interest you.”