I'm Not Lazy:

This is from a much longer post at Thought Catalog, which rings true (hat tip to a-thousand-words, where I first saw it):

It turns out procrastination is not typically a function of laziness, apathy or work ethic as it is often regarded to be. It’s a neurotic self-defense behavior that develops to protect a person’s sense of self-worth.

You see, procrastinators tend to be people who have, for whatever reason, developed to perceive an unusually strong association between their performance and their value as a person. This makes failure or criticism disproportionately painful, which leads naturally to hesitancy when it comes to the prospect of doing anything that reflects their ability — which is pretty much everything.