Now to answer the long the not so easy question. As requested these are my thoughts but I have to rewrite them. My original writing exceeded 1000 words, way more than I like to read on a forum post. I'll save it for my Blog.
So, What goes on? Why do we procastinate on difficult task to the point of putting them aside to do easier task. Like I did in answering the other question first.
So for starters purjo you're not the only one that suffers this tupe of procastination.
The answer is remarkably simple ... reward.
When we know were are close to being rewarded for our efforts we become faster and more accurate at performing the task. Then the task is time consuming, because it is confusing and we don't what to do next, know when or how we will get done we don't work as well at it.
It the same as putting off homework or assignments and waiting till the last hour to study for an exam. Often there is no forseeable reward for our effort so we rather do something that does reward us. Sooner rather than later.
AS for unfinished task. I think we all have closets and garages full of them. I know I had some Personal learning courses from years ago that were haunting me waiting for me to finish listening to them. I finially did myself a favour and threw them in the bin $3000 worth I calculated but a relief. I finally admitted to myself I didn't like the presentations.
You'll let go of them at some point. 
Developing a strategy for motivating yourself when there is no reward or a heck of a wait before you can be rewarded for your efforts is possible. Chunk early and give yourself plenty of finishing points. Getting something finished to a certain point can often be a reward in itself. Then you might consider creating rewards.
Sometime the task just hangs around until you finally stop thinking about it (good or bad) and just do it.
The reason knowing you are there is a reward for your efforts helps is because you get a boost of activity in you brain that keeps firing and you to work faster and with more accuracy. It stops firing when you have almost finished the task.
Brain research also shows if the reward is ad hoc you will work at it but not as accuratly or as fast.
If there is no reward. You will perform poorly if at all.
So when an easy task comes along the brain fires in favour of that. (Finish a task is often the reward).
Deferring short term gratifcation for long term benefit is an emotional brain verses logical brain problem. Yep, again natural parts of the brain firing away here tyring to motivate us. Humans are not the only ones that have this problem. So do penguins. Some put more work into diggng a burrow while others prefer to just nest on the surface. Sort term reward nest built faster. Long term problem heat stroke. The ones that spent the time digging burrow have a nice cool and shady spot.
So a possible solution?
The New Options Generator, chunking the task into smaller parts or occasionally say no to easy task.
If I knew the exact be all end all answer for this human problem... Well you know. 
Alex
