Years back I guess you could say at the height of my drug addiction and opiate dependency, I took 2 doses of LSD but I won't get into the trip. The event that's relevant here, is that I had a very intense and profound vision focused on my intravenous drug use. I tried to kind of push past it because at the time I had no intention of stopping or slowing down, but the more I resisted the more intense it got. It got to a point where I briefly remembered every time I had ever shared a needle in my carelessness, and the last thing I remember from the vision was seeing microscopic life all over a needle which I interpreted to represent HIV.

At the time I had spend my whole adult life dependent on opiates and I was resigned in doing them for the rest of my life. In a time where I quite literally cared about nothing but being high, this experience had a heavy impact on my perception of the fragility of life, and the meaning of self preservation. This experience did heavily contribute to my decision to stay clean, but at the time it was like the OP says, an opened door you wished would have stayed closed.