I smoked several times a day for 14 years and had a seriously high tolerence level. Then I stopped completely for 5 years. When I started smoking again I found my tolerance had gone completely. I only needed a little bit to get really high. What I didn't get back, however, was that crazy, happy laughing high that I used to get when I first started.

My theory is that the crazy high you experience when you first start smoking has more to do with your mind and body experiencing a new sensation than it does with tolerance levels. When you quit for a while your tolerance goes away but the memory of that new sensation is still logged into your brain. So, unless something happens that completely erases all of your memories, you'll never get it back.