I like your take on the being overwhelmed part John Amiscaray.

Let me add my two cents! I think I can add a little to the conversation (I'm a psychologist after all) :D

The usual dopamine rationale is so broad that it ends up being pretty useless as an explanation. The underlying premise is that constant excess dopamine ends up "desensitizing" people to the relatively lower amount of dopamine produced as a result of working.

But this leaves out other higher-level factors, like executive function, and emotional self regulation. Which may or may not be related directly to the amount of dopamine. But we know that people procrastinate as a result of poor executive function (broadly, your brain's ability of regulating attention) and poor emotional self regulation (roughly, being overwhelmed and failing to power through with motivation).

We can clearly see this in cases of ADHD (like myself) where people just plain forget to do stuff. Or spend a lot of effort starting, only to be easily distracted and having to start again, which is really frustrating.

Also, the dopamine explanation leaves environmental factors out completely. If the least boring thing that is physically possible right now is working, you would have very little trouble being productive. As working would at least be better to being bored.

In comparison to a situation where you have other, easier and more stimulating, options easily available. So the motivation to do stuff is affected quite a lot by the environmental context you operate on.

Of course, all these factors will have an effect on dopamine levels on the brain. But thinking like this leads to actionable insight, while the dopamine rationale, by itself, doesn't.

Hopefully that was interesting :D