1. Just do it.
Seriously. Stop being a pansy. Stop relying on excuses. Butt in chair, hands on keyboard and write already.
2. Listen to these guys.
If Writing Excuses doesn't make you want to write, I don't know what will. Brandon Sanderson, Dan Wells, Howard Tyler, and Mary Robinette Kowal are all authors who support themselves with their work, which I think for a lot of us is the dream. They have really good input in 15 minute snippets. Definitely worth a listen.
3. Challenge yourself.
I love writing prompts. Check out Yeah Write, Trifecta, and Write on Edge for some easy prompts that also involve winning. I like winning.
4. Read a book.
I know this doesn't work for everybody, but reading always makes me want to write. I dissect plot elements and see what they did right and wrong, and it makes me want to work on my own writing. It's a good way to jump start your brain.
5. Set a goal.
500 words a day. It's not a lot. If you do that every day for a year you will have 182,500 words. That's three novels, folks.
6. Set a timer.
Just write for an hour, ten minutes, five minutes. Any words are better than no words. And chances are once you get going you won't be able to stop.
7. Get friends.
Twitter is a veritable hub of writers aspiring to be authors. Check out the hashtags #amwriting and #writeclub for some excellent people and support. Keep your eyes peeled for local writing groups at the library or on MeetUp.com. If there isn't one around, start one! Writing is lonely business. Make it less lonely.
If writing is what you want to do, it shouldn't be 100% forced all the time. We all have our down days, but if writing is what you want to do, there shouldn't be much in your way of doing it. Don't let yourself get in the way of achieving your dreams!