I've been there... several times. It's never fully stuck, as I always seem to come back to psychedelics and even opiates from time to time.
However, the last time I had the thought that 'I'm never going to take drugs ever again' I managed to flush an insane amount of my stash down the toilet. This included a hefty stash of mdpv and methylone. In retrospect, I'm glad I flushed those... because I was starting to use both chemicals way more than I was comfortable with... and it took a heavy trip on LSD for me to realize that. Thank god for that, though, looking back now... who knows how bad things would have gotten had I not flushed them.