you focus on the crosshairs, on the target, that is where the bullet is going to go if you do things right.
The other fundamentals should be executed without thought. We know how to press the trigger, if you concentrate on the trigger you mind will wander down to the trigger and take your focus off the crosshairs which will probably start to drift off target. If you think about your breathing you'll hold your breathe. We breath without thinking about all the time. The only time you need to think about your breathing is when you swim underwater. All you need to know is the shot should break at the bottom of the breathing cycle.
Next time you are driving your car on the highway doing 65, look at your hands.. see the subconscious micro adjustments our hands make to stay between the lines. Same thing... you focus a couple hundred yards down the road, not at the tip of the hood. You can talk on the phone, change the radio station, eat your breakfast all while your hands are keeping you in your lane. Why, repetition.
If you practice correctly the repetitions will create positive neural pathways so we can execute the firing task on a micro level. Milliseconds and Millimeters of control. So what does that mean, you watch where the bullet needs to go and focus on that... let your body do its job without distraction or confusion,which is what we interject when we over think the problem.