It is difficult not to be bothered by a fly in a closed room.
For as much as you force yourself into a state of flow, the fly will make its presence noticeable incessantly, and eventually you will be left with two options: either be distracted by it – shooing it away, having your pressure and heartbeat rise, calling it names, trying to catch it -, or open the room to let it out and continue your activity.
There are two points to this short and conventional story.
The first is that, more often than not, we choose the distraction over the solution. It feels easier, we don’t have to stand, it gives us a prompt and lasting excuse not to do the work (well), and it feeds an illusion of time passing.
The second is that if we want to do the work (well), we first of all need to keep flies and other distractions out of the room where the work is done.
It is that simple.