Once the mind has been trained that 'alcohol makes me feel good', the brain will periodically recall this, and shoot the command up to the decision-making centre.
In a healthy person, the decision-making centre is well informed by experience, so, if alcohol has caused a ton of problems, the decision-making centre trashes the impulse, saying, 'On balance, no.'
In alcoholics, the decision-making centre is great on other stuff, but is faulty on alcohol. Sometimes the defence kicks in; sometimes it doesn't. It's like a light bulb that flickers on and off. Consequently, if the impulse coincides with a failure of the defence, the impulse turns into a decision, and we drink.
What's the solution?
To live life based on something other than my own thoughts and impulses.
AA trained me to live based on the four Ps:
Programme: the Twelve Steps, Traditions, and Concepts
Principles: the ideas, standards, and values of the Programme
Prayer: asking God what to do
People: asking sensible people what to do
When I do this, I unlock the Power, which comprises Direction and Strength.
Power needs both. Undirected Power achieves nothing. Unpowered Direction achieves nothing.
Direction + Strength = the Power Greater Than Myself.
This Power is so Powerful, that, if trusted and surrendered to, allows body impulses to dissolve into nothing. So, even if they arise, they do not turn into action, and we do not drink.