The only time I've had sucess with any sort of sustained sobriety is to do exactly what the health care professionals tell me to do. If they say 30 days, do it.
I was told I needed 5 months in rehab (inpatient) and I did it. It was tough and it's a big committment (any amount of time away from home is a committment).
I'm now in a sober house (for another 4 months away from home) and it has been the best decision I ever made. Except I really didn't decide anything. I'm just doing what I'm told.
It's simple really. Just follow directions.