If you have a subject to paint, then you are always thinking of the end result, not of what exactly you are doing at every particular moment. Conscious of the apple on the stand, not the exquisitely intimate contact of each stroke of brush on canvas.
It’s like when walking, being aware of the destination and thus not of the wondrous sensation of each foot in turn meeting the ground and moving on it. Our minds are set ahead, not living in each precious moment (Circulation-Sex 4). Oblivious to all the beauty around us, we must get there. We must paint the apple.