The thing about ADHD is that the "lack of reward chemicals in your brain" doesn't just mean that you don't want to do any tasks that don't feel particularly yummy :(, it means that your brain will look at chores and tasks that need to be done like "doing this would be painful and tedious for absolutely nothing to gain from it, Do Not Do That." The same thing that your brain tells you about everything else that would feel really bad and hurt the entire time that you're dying. The part of your brain that stops you from doing the thing is the same part that keeps you from shoving your arm into a wood chipper.
With unmedicated, unmanaged ADHD, "I have to do this assignment or I fail and my life will be ruined and I die" feels like a SAW trap, every single time.
People who roll their eyes at this stuff and wonder how anyone could possibly be hindered by something "just in their mind" have no idea what helpless slaves they already are to their brain. Their brain just happens to make the right juices in the right amounts that it motivates them to action more often, and as a result, they believe they're in more control of themselves.
