I can do this, today and every day, if I want it badly enough.And I get her point - it's why I use New Year's for fun resolutions (under consideration this year: circus camp, learning how to "cab whistle," and learning how to ululate) and, if I want to change or be better, I just do it when the idea occurs to me.
But there's a reason the week between Christmas and New Year's is commonly known as clean out your desk/email inbox week: fresh starts are nice. Sure New Year's is kind of an arbitrary time (why not, for instance, the first day of spring?), but it's a commonly agreed upon arbitrary time, and that's why it works for people.
So how do you help yourself stick to your resolutions? Well, you could take my route and only resolve something fun. I started doing it probably about 10 years ago, and I've kept every single New Year's resolution I've made since.
But the answer's right in front of us: accountability. If you want to make a more serious resolution, find someone who's willing to hold you accountable for the results, and see the change you wanted to create become a permanent part of your life.
And whichever direction you choose to go - fun resolutions, serious resolutions, or no resolutions at all - have a very happy New Year!