There's a poem called "The Art of Disappearing" by Naomi Shihab Nye that appears on The Writer's Almanac with Garrison Keillor. It's basically about learning how to say no to other things so you have time to write. I particularly liked this stanza:
When they invite you to the party
remember what parties are like before answering.
Someone telling you in a loud voice
they once wrote a poem.
Greasy sausage balls on a paper plate.
Then reply.
You can read the whole poem HERE. You may even want to print it out and post it near the door!
I don't particularly like that question that when you're on your deathbed, what will you wish you had done more of...on my deathbed I think I'll be wishing I'd had a better doctor. But it's true that our time is finite and if you don't get around to writing what only you can write, you may regret saying yes to too many other things that ultimately are less important.
(My online Writing Breakthrough Strategy Program has helped lots of people set and achieve their writing goals--it can help you, too. Get the details at www.jurgenwolff.com.)