When it comes to fiction writing, I love creating characters and watching them run with the story under my pen. I spend a lot of time at the office coming up with exciting ideas of what and who to write about, and on the way home, I can't wait to get to my desk or notebook. However, when I walk through the door, I inevitably turn on the TV, play a video game, or find some other task to take up my writing time. We all know people like that, right?
It's not that these things are more exciting to me than writing. I've boiled it down to that they are easier to do. Before I can write, I have a lot of fleshing-out that must happen to my ideas before I can get to the "letting the character run with the story" step. Characterization, motivation, setting development, plotting, research, filling in any holes I've discovered through the prewriting process...all before I've put pencil to paper. It's much simpler to turn on a distraction.
I think my problem is too much prep work. By the time I finish it all, I usually burn out on the story and lose interest in writing it. Is there a way to determine the bare basics of what I need to have figured out and to deal with the rest in the process of writing and revisions?
Edit: I've received a number of great answers so far, each of which contains things I plan to apply, but I feel my question needs some editing to better explain my writing approach.
As I've mentioned in a comment below, I have had tremendous success with forum roleplays. In this context, much of the "prep work," particularly setting and the overarching conflict, is already taken care of by the forum creator. I have only to create a character with their own desires, motivations, and obstacles before I can jump in. I realized after my comment that I enjoy plotting in my roleplays as well, but I usually do this as I'm writing, in collaboration with other players I'm working closely with. Usually I get in contact with them to suggest future events.
I have tried to create a couple forum RPs of my own, but have burnt out before getting either of them running.
Obviously developing setting and overarching conflict will have to be skills I develop to be a successful author. In the meantime, I think the closer I can bring my writing process to my roleplaying process, the better off I'll be. Any suggestions?