Finishing

I've started a lot of writing projects.  That's the problem.  I start them and then don't get any further.  I get somewhere in the middle usually and even though I know how I want it to end, I just don't seem able to get there.  This is, I believe, why I'm not published yet.  How can I be published when I never end things to send them off?

It's not a fear of editing.  I love editing (yes, I know I'm weird).  It's not even the fear that they won't be good enough - I know I'm good with words (I'm not bragging, it's the only skill I have), though yes, I believe my ideas could sometimes do with a little work.  But that's nothing that can't be fixed.

The problem is I'm lazy and I don't have much self-discipline.  I get to a point when I am bored with a project so don't push myself to finish it.  Instead I go to a shiny new idea and start that.  I have lots of starting paragraphs and even pages stored on my computer, more than I'm even aware of. 

It is good when I run out of ideas and reading one of my beginnings can spark so much excitement.  But that's rarely enough to actually finish anything.  The only pieces of writing I've ever actually finished have all been assignments for my uni course.  And that's the main reason I took a writing course - to force me to finish.  But what about next year?

It seems I am going to have to come up with a better system with sticking to one piece at a time until it is finished, if I ever want to get published (which, of course, I do).  So any tips on staying power?  I've tried self-deadlines but they don't work for me.  Do you have this problem?  How do you deal with it?