How I see it: You can start - or stop - anything you want at any time. Life is like a buffet, you get to taste lots of different things to see if you like them. Or life is a stroll through a forest with exciting little paths going off in all directions...
I don't believe in resolutions... just experimentation and tasting. If you like something you'll stick with it - if not, then you can move to something else. There are so many things to "taste" in this world, this life, it's silly to hold back on anything that takes your fancy.
As an example: At the beginning of 2012 I quit my job, started a website on physical-training, didn't make any money fast so moved on to starting a business writing and illustrating picture-books. I was on my second book when I discovered live-storytelling and I was hooked. This led me to a renewed interest in songwriting (something I'd given up 10 years earlier). So I abandoned the book-business and made an album of songs. The other things weren't wasted - they led me to where my heart lies. Now I'm going travelling in a camper-bus to sing around Europe, learn to be a good storyteller and performer, and build a following for my new blog (thewriterandtheriver.com).
The thing is... even though I feel I've found my calling, I could find something new along the way that I enjoy more, and consequently end up doing something completely different. Paths lead to other paths, and walking the path is the purpose.