Dude, speaking from my own experience, the only way I found that worked to reduce my tolerance was to take a vaca from the bud. I know, its sucks but it works. The time it will take is all a personal issue; everyone is different. I did it for my girl (at the time). I was a daily toker, morn, noon, night, & snacks for about 4 years straight. It took a while and once you start again you'll adapt quickly, if you go back to your old ways. Try moderation (it helps).

Now my girl is gone and I can enjoy as much as I want again. Yee-Ha!