I'm glad to hear this as well, and even more glad to hear it today. Despite being medicated, I still struggle to focus on activities which are not intrinsically interesting to me. Even though I want to focus, paying attention to work that is not intrinsically interesting to me requires extreme levels of self-control and leaves me feeling mentally and emotionally drained. And just yesterday, when I was unable to access my medication for 24 hours, I had what can really only be described as a nervous breakdown at work from trying to make myself focus. I don't want to use this as an excuse for not achieving, but having scientific evidence that this is a "real" thing--and not just a set of bad habits and lack of concer--helps reduce the stigma that only compounds my problems. I don't want to be held to a lower standard, but I do want to be afforded the grace given to people with other mental health issues.
I also have that problem, inability to concentrate on non-intrinsically-interesting mental activities combined with huge emotional/energy drain when I force myself to.
I'm curious how normal it is for humans to be able to concentrate on non-intrinsically-interesting mental work, though. I can believe that there's a range of skill in it, but can't seem to find data on the range. From what I can tell in academia, very few people actually have the level of concentration considered "normal" or "expected" without either taking some variety of medication, or mustering exceptionally draining bouts of force-yourself-to-concentrate. There are a few exceptionally-good-at-concentrating people, but I suspect they're actually the abnormal cases, representing the top 10% of some bell curve.
It'd be interesting to see data, anyway. For example, I'd be interested to know what the average +/- 1 or 2 stddevs is among the population on a test of ability to concentrate on non-intrinsically-interesting mental work (if that can somehow be measured). Similarly, for diagnosis myself, I'd be more interested in a percentile number than anything; rather than just saying that I suffer from poor concentration on non-intrinsically-interesting tasks, I'd like to know how poor my concentration is relative to the median. Does "poor" just mean that I can't match what the top 10% of the population does? Or does it mean I'm in the bottom 10%?
The standard workplace expects you to concentrate on work for 8 hours a day. Barring the occasional firedrill (which provides enough stimulation) I struggle with it too. Does nobody else surf the internet when they should be working? Do people actually work for a solid 8 hours (not just be at work, but actually working?)
I think the idea of it as a bell curve is a good one - ADHD is supposed to be the poor bottom end. But I do wonder what average really looks like.