I spent the better part of the last year (granted, I was also teaching myself a number of programs) spinning my wheels and not accomplishing much.  I was always working, but rarely finishing before I got bored and something else sparked in my brain and I moved on to another project - which I also rarely finished. lol

Its still something I have to fight, but I feel like I overcame this really rather recently.  The key for me was to show someone the work after I completed it.  Its sometimes people on a forum or gallery, sometimes a closer friend or my husband (though I have to watch that because its easy to get him to accept my excuses) - someone that cares about seeing the completed work and is waiting to see it and appreciates it.  Then I make a committment to having the next project done at a certain time, and I make as early of a deadline as I think I can possibly complete it by.  If I have too much allotted time I will waste it, its a proven pattern of mine.

The accountability of someone waiting to see my work, that I know enjoys it, is what has kept me pushing forward.  Open ended deadlines or work no one knows about gives me way too much freedom to procrastinate or get distracted by something else to do.