If it's really that hard to get engaged into something that you aren't innately interested in but that you know you "should" do, I would seek an ADHD diagnosis. It's a pretty big symptom. Sometimes it really is not possible and even if it is it's extremely difficult and you feel dumb for it (but obviously you shouldn't, it's not your fault). It's like your mind throwing a tantrum and refusing to engage with the work at all.
The difference is really not being able to focus if it's not interesting. Your brain will constantly turn to other stimulation if it's not getting it from the current task. Sometimes you might be able to do it, and other times you won't. That's one of the most frustrating parts of ADHD. You feel like you've done it before, so why can't you do it now? "Normal" people can still focus (or get started) even if something is not interesting, they just have to start.
Most people won't like to do uninteresting things, but the threshold for boredom is extremely low in those with ADHD so they will struggle a lot more to stay focused. It's a spectrum unfortunately, so there's no one definitive measure that says "that's definitely ADHD". To be honest, if you find yourself seriously questioning/wondering about whether or not you have ADHD it probably means you're struggling to an extent and aren't 'normal'. Otherwise, it wouldn't be something you are questioning.
Not wanting to do it and not being able to do it are two different things. To an adhd person boring tasks aren't just boring to do, they are impossible to do even if they were paid a million dollars to do it.
I call it not being able to put one foot in front of the other. You will find all kinds of distractions to try to not think about it, because to think about it is almost physically painful.
