If you are a writer, you write because you love to write. If you don't like to write, you don't do it. It's one of those things you love or hate. Me? I love to write. But like all writers, sometimes it's hard to get started. Why is that?
If you love your job (and that's what writing is for writers), why do you delay beginning?
Sometimes, it's lack of time. This can be solved, however, by scheduling the time to write. Clear everything off your calendar for however much time you can spare, and use that time to write! It's your job--make the time!
Sometimes you don't write because you don't have any ideas. Once you complete a project or novel, where does the next one come from? It may already be there, it may not. And if it's not, start looking. Look in your notebook of ideas. Look in the pages of research you've clipped from magazines. Look at the books on your shelves. Think about a favorite memory of yours. Something somewhere will trigger an idea.
If you have an idea, but not sure which direction to take it, start freewriting. Just write down random words associated with the idea. You never know where this exercise will take you.
You may just come up with the next best-selling novel.