What we practice is what we get good at.
Start very close to the bale and focus on the finest point possible; Pull with your elbow; Hold; Breathe. Shoot only one arrow at a time.
When you get good at this,, back up two steps, or maybe even three. It may take days to even begin to re-program.
The arrows fly where the mind puts them. If I'm scattered, so are my arrows. Narrow your focus to the smallest spot possible. You will always shoot right around your focus... If that focus is small,, great!
Don't shoot if/when you're stressed. Just go out and make a meditation out of it. I like to shoot in the dark. It reduces the distractions and allows you to pay attention to "the feel".
Shooting dandelions and clover can help, too,, as long as there's no rocks in the yard....
I tried a clicker and it just gave me more stress. I like what BowsanAiros had to say, a few lines up.
Good luck!.... Ken