The research shows that people who seem to have a lot of self-control actually spend less time resisting urges. Instead, they set up their lives in such a way that they are not constantly faced with temptations, so they don't drain their willpower as quickly. They also tend to eat healthful food, get enough sleep, keep a tidy workspace, keep track of their progress, and reward themselves often. And once you've formed a good habit, it becomes almost automatic, so keeping it up requires a lot less willpower.
Some people argue that resolutions are doomed to fail, or even that they prevent us from enjoying the present. But success is not unrealistic, especially if we're armed with some knowledge about human psychology, and having goals does not require us to be exclusively future-oriented. The payoff for rationing your resolve is simply more control over your life, and so a life closer to the one you want to live.