I won’t order a side of chips and guacamole with my burrito. I won’t drink alcohol until the weekend. I won’t smoke anymore cigarettes. I won’t eat anymore cake. Each day we’re faced with decisions that affect our lives in real ways. Eating more than we should adds weight to our waists, and alcohol and cigarettes simply aren’t good — the former, a little at a time. These are only a few examples of the things we try to control ourselves with, and with Lent starting today, millions of people around the world will give up something for 40 days and 40 nights. How? With willpower, of course.

Some people say willpower is like a muscle; the more you build it, the better you become with controlling what you do and don’t do. David Blaine, the self-named “endurance artist” who has spent a week suspended underwater in a 2,000-gallon tank and another week buried alive inside a coffin, credits willpower training for helping him accomplish these stunts.

“Getting your brain wired into little goals and achieving them helps you achieve the bigger things you shouldn’t be able to do,” he told Roy Baumeister, a psychologist at Florida State University, in his book Willpower, according to The Boston Globe. “It’s not just practicing the specific thing.”

Willpower is essentially just self-control; choosing a more valuable reward in the future over a less valuable one right now. It comes from at least two neural systems in the brain that play roles in decision-making, impulsivity, and of course, the feelings of pleasure and reward that come with them. These systems are like a good and bad conscience; a reactive system in the amygdala assesses the pros and cons of an immediate reward, while a reflective system in the prefrontal cortex does the same for future rewards. One 2009 study showed the interplay between these two brain regions — so-called dieters were able to put more emphasis on the healthiness of food and less on its delicious taste, which is a stronger stimulus, while those who couldn’t resist did the opposite.

According to the American Psychological Association’s (APA) 2011 Stress in America Survey, lacking willpower was considered the number one reason respondents couldn’t follow through with healthy lifestyle changes — 27 percent said it was the most significant barrier to change. Simply acknowledging this is the first step to building willpower. Speaking to the APA, Baumeister said establishing motivation for change and setting a clear goal is the first step to accomplishing it. Then comes monitoring behavior, and finally, willpower.

Those last two parts are particularly difficult to control if your willpower isn’t there already. That’s because “willpower is a lot like stress,” Stanford University health psychologist Dr. Kelly McGonigal told the university’s Scope blog. But rather than an external conflict triggering a fight-or-flight response, it’s an internal conflict, and this sets off a number of other mind and body reactions that block willpower from working, as getting an immediate result is perceived as more important.

Relaxing — and even meditating — is perhaps the best way to boost willpower, as it puts the body in a calmer state known as a pause-and-plan response, McGonigal said. When this happens, energy that would normally be spent on the stress-related adrenaline response instead goes to the prefrontal cortex, where impulses and cravings can be overridden. Combining this with physical activity, which is a known stress reducer, has been shown to improve willpower.

Taking these steps becomes even more important at the end of a long day because that’s when we’re most vulnerable to slip up. Self-explanatory, it’s known as decision fatigue, and it’s based on the fact every day we’re making increasingly exhausting decisions. What train do I take to work? What’s for lunch? Should I drink another cup of coffee? Should I go out after work or just go home? By the time you actually get home, that ice cream craving is stronger.

A 2000 study from Columbia University showed this by setting up a grocery store sampling booth for jam over two consecutive weekends. On one weekend, they offered 24 different types of jam and on the other they offered only six. They found that while more people approached the 24-jam booth, they still only tried one or two, which was the same amount as people visiting the six-jam booth. What’s more, only three percent of those visiting the 24-jam booth bought jam, having experienced “choice paralysis,” while 30 percent of those who visited the six-jam booth bought some for their homes.

Kids with stronger willpower have been shown to have higher grade-point averages, higher self-esteem; be less prone to binge-eating, and alcohol abuse; and have better relationship skills. As adults, they grow up to have greater physical and mental health, fewer substance-abuse problems, and better financial security. Getting there may be difficult, but accepting any blunders along the way and trying again is the key to success. For those of you giving up something for Lent, however, the time to control yourself — without the blunders — is now. Good luck.