Wow. I feel like I just read a post about myself! I also loose interest really fast in the same way you do. If I don't see results as soon as possible I will scrap everything.
I wonder, do you plan your projects to the end? If you plan first you will be able to scrap the project before you even start. hehe.
I have a suggestion. I once tried to make a feature film using the Sims 2 game (In over my head), so I decided to make some Motivation Shots. First I worked on the intro to the film and made it really captivating. Then I worked one scene I thought would be really cool, and made it really good also. Then I got to a part that was just impossible for me to do without real people. And that is where I began to break down. And the project didn't get finished.
Even when I have a lot of motivation, all it takes is a little demotivation to discourage me. I have these big ideas, but thing is, I don't have all the knowledge, or patience to learn the knowledge, to implement them. I overwhelm myself.
I wonder, do you have this same issue also?
What you should create for each project are MOTIVATORS. And it doesn't help to have friends who are not motivators (good ones that actually motivate you). You kinda have to set yourself up on purpose. For instance, if you have a smoking problem, get rid of your friends who smoke, destroy all of your cigarettes (if you keep even one, you loose already. Don't throw them in the trash where they can be retrieved.) Ride your car down to "E" so that the only place you have gas enough to go to is an important place, like work. hahaha.
This is sorta extreme, and chances are you will loose on the consistency part.
I wonder, do you have a consistency issue also?
After I cry and complain about my failed life, I just think, ''ARGHHH Whatever!" Then I go at it full steam!