This is a big question that I think about often. Myself, I don’t believe the term “lazy” defines anything substantial or informative. I’m glad you left it out for me to compliment you on. :) My conclusion so far (skipping a lot of background) is something like this:
For many many many reasons I’ve come to believe that the human brain is incapable of diverging from a path of thought and behavior that it has rationally concluded is the most sensible.
Because of that one conclusion (which some share and others do not) it seems obvious to me that the only reason a person fails to do something they “want” to do.. is because during the periods where doing the action is possible, they simply don’t happen to “want” to do it. They actually want to do something else instead. This is a very time sensitive concept, by the way; I’ll try to make an example:
Bob may have wanted to do action X (most likely dishes!) while he was at work, but he needed to get home to do it. Bob may have wanted to do action X while he was at home but he needed to wait for his room mate to get home to get started. Bob may have wanted to do action X while he was home with his roommate, but he needed his roommate to remind him. Bob may have wanted to do action X after he was reminded by his roommate at his home, but he needed encouragement rather than a demand.
My point is, that Bob is actually never existing in a period of time where his focus is on the task itself. His focus is always on satisfying external conditions. In a very real sense, bob is ignorant of the task at hand. While ignorant of the actual task, he is incapable of “wanting” to either start or finish it.
Wanting something is simply a matter of believing something “should” be done. Should according to your own definition, no one else’s.
To his roommate, he looks lazy. And maybe lazy would make more sense if it specifically defined someone who fails to apply the necessary focus. Dishes get done when you focus first on turning on a tap. Bob never manages to focus on or believe that is necessary and as a consequence the dishes never get done!
So, I believe the real reason why people don’t do things they mean to do, is because they technically don’t know how to do it. They are incapable of focusing on the basics, the start of the project. Perhaps they only see the end result and imagine loosely the amount of energy that would have to be expensed to do it. Whatever the case is, the mind is simply not focused on the task. The mind does not believe it to be crucially necessary and beginning the task is never fully achieved.
Another example: Ask a business man downtown at lunchtime to climb a tree. He will be hesitant even if he is physically able… that is, until you unleash a bear on him. As soon as he believes climbing a tree is worthwhile, he will find it easy to decide to do.
Sorry for the wall of text/thoughts. I’ve wanted to examine this for some time. (and there’s still more too.. something about habits and the roll habits play in preventing or making easier the virtue of starting a task. without habits it’s really hard to do things that others have spent time creating a habit of. the solution in such cases is to spend time developing the habit. this takes effort.)