If you're already struggling to keep your New Year's resolution, consider this: you might have picked the wrong one. People tend to make resolutions that don't reflect what matters to them most, Stanford University psychologist Dr. Kelly McGonigal said in a recent TED blog post.

"Even if that behavior could be very valuable and helpful -- like exercise -- if you start from the point of view of thinking about what it is you don't really want to do, it's very hard to tap into willpower if there's no really important 'want' driving it. The brain system of self-control has nothing to hold on to," McGonigal said. 

McGonigal defines willpower from a cognitive science perspective. The human mind is full of competing systems -- for example, your ability to think in the short-term and in the long-term. "Willpower is the ability to align yourself with the brain system that is thinking about long-term goals," she said.

So if you're having trouble getting enthusiastic about the long-term gains from your resolution, you might want to rethink it. Here are three tips from McGonigal for mustering up the willpower to see your goals through. 

1. Choose something that you actually want to do. Do not form a resolution that you feel completely averse to. Vowing to do something that you don't really care about is setting yourself up for failure.

2. Ask, what will you thank yourself for?  "On January 1st, 2015, looking backwards -- what are you seriously going to be grateful that you did?" McGonigal posed. The answer to that question can help uncover a truly authentic goal.

3. Bribe yourself.  When it comes to a something like exercise, your short-term and long-term thinking might not be aligned. How can you motivate yourself now for a later outcome? "Give yourself permission to do whatever you don't want to let yourself do -- like read trashy gossip magazines, or download a whole series of a TV show that you can plop on in front of you on the treadmill," McGonigal said.