Google defines a resolution as, "a firm decision to do or not to do something." Why wait for New Year's to make a change?
The moment of action immediately follows the moment of decision, or recognition.
"I want to eat healthier, travel more, lose/gain 10 pounds, be more outspoken, stop self-destructive behavior, volunteer at an animal shelter, be more intentional, run 3 miles a day..." It just keeps going, and it's wonderful.
SO DO IT. Your aspirations and self-improvement dreams are not some far-off phenomenon that are going to happen somewhere down the timeline. They're your immediate life. "You" changes every minute of every day, with every thought you think and every decision you make and every action you do. So, own it. Own every single version of you, and use your constant progress to mold yourself into your goals.
Once you've felt the whisper of a direction to something greater than that which you are, take off running towards it, and never stop. Bolt towards it with all you've got, all you are, and throw a little hope towards it, too. That's the best part about growing- you can run in SO MANY totally different directions all at once, and you're still on your way to becoming...you. Each time you tell yourself, "I'll start tomorrow," or, "It'll be my New Year's resolution," you're wasting time, and you do not have the luxury to forfeit the hottest commodity in the universe. When you feel a spark, or maybe it's a constant, gentle tug, and know what you must do to quench that feeling, you must do it. Any delay is nothing other than a resolution that you choose not to reach your maximum potential, a resolution to slightly minimize your own greatness.
You become your actions, so make them good ones. Make actions: movements that change the stakes of living, that are intentionally, powerfully, and confidently driven by you. You are a runner before you have taken the first step. You are a student before you have cracked the first book. You are an explorer before you have stepped foot out the door. Deciding TO DO something different is really just compartmentalizing the decision TO BE someone new. Once you have decided to be someone new, why on earth would you wait to start living like it?