To be clear, there are medical issues around withdrawal from alcohol, and it can certainly be life threatening as the depressant is removed and all the systems which had been laboring under this weight are suddenly unburdened. Stuff under autonomic control like blood pressure and heart rate can go haywire, and medical intervention can become critical.
If anyone has any doubt about whether they might need medical care, please please please see a doctor.
Beyond this, failure cannot happen if it can't be imagined. A level of confidence in success pegged arbitrarily and constructively at 100% eliminates any chance of failure. It's a mind hack, true, but it will do what it says on the tin - permanent and planned lifetime abstinence. I believe in my deepest knowing I will never drink again, as sure as anything I can conceive. And so I won't.