Paying attention
Attention is often considered to be a good thing. After all, if you want to do a good job at something, you should pay attention, right? I'd like to argue that attention is, if not a bad thing, at least a dangerous thing that can often be the harbinger of problems.
Something that needs your attention is something that is unstable (or, rather, negatively stable). That is to say, if you withdrew your attention from it, it wouldn't keep going the same way. That could be because it's a problem that you're paying attention to in order to fix, or an area you're paying attention to in order to improve. Either way, it only keeps going as long as you keep focusing on it.
By contrast, something that's stable doesn't much care whether you're paying attention to it. If you brush your teeth absent-mindedly while thinking about something else, you're not going to suffer a catastrophic breakdown in dental health. If you throw a frisbee around every now and again but don't take it seriously, you're not going to have your skills decline to the point where you may as well not bother. In some cases, something that's stable enough can be ignored entirely, though it's pretty difficult to make a system that stable over long periods of time.
The issue with attention is how limited it is. If you're only doing one thing and that thing requires constant attention, well, maybe that can work. But what about when another thing comes along? Not just work, but friends, family, personal development and general life tasks. When two things want attention, only one is going to get it. If they both need attention, then one of them is going to fail.
The other sense in which attention is limited is that it is taxing, and whatever resource it uses can run out. A task that you have to pay careful attention to the whole time you're doing it is a task you can only do for a tiny fraction of time compared to one you can just do inattentively. Compare how long you could spend stacking wood vs doing maths problems, or chatting vs talking through a complex idea. Things that require attention are harder and more fragile.
Put these parts together and you see how dangerous it is to rely on attention. Not only can you only do one thing that requires attention at a time, but you can't even do that thing very much. Which, again, isn't to say that attention is bad. But it is a cost that you pay for getting something done. If you pay that attention once, to gain some improvement or fix some problem, that's fine, but it's very easy to end up paying and paying again. And if all your attention's used up, how are you going to pay for the next thing?