>> Underlying this state of “automaticity” (as cognitive psychologists call it) are mental processes that can be executed without paying attention to them. These processes run off without conscious awareness—a chain reaction of mental events. We don’t perform all tasks automatically, but many can be performed this way once they are well practiced.
It is not the case that we do not pay attention to the tasks, but that we pay attention to them with different faculties than the mind. For chopping cucumbers, if we are chopping cucumbers and talking to our mother at the same time or singing a song in our head, we are utilizing our physical functions rather than mental. It is not that we do not pay attention to the chopping, but that we use our body to do the paying of attention while we use mind elsewhere.
>> this is one reason why some experts appear to “choke under pressure”: they think too much about the mechanics of the task at hand.
If you're trying to do physical tasks while also doing mental tasks at all, then you are thinking too much.
>> skilled golfers performed substantially worse when they focused on their swing
Now they are realizing they have bodies, and trying to see what they are doing, mentating while also trying to use that physical-only skill that they had developed under very different circumstances (without mentation).
One may also hear about how meditation or mindfulness 'destroyed' someone's life or 'made them crazy'. It is the case that many are unable to process the pain/unpleasantness of fully experiencing one's being in all its horrror. Truly looking at oneself can probably be achieved by more if they were to take it in small doses with plenty of mindlessness interspersed throughout their practice, rather than trying to 'drink the ocean'.
Edit: clarity/verbiage.