I have experienced this also.I smoked daily from the time I was fourteen until I was 43.I enjoyed smoking and it was more of a lifestyle than a way to get high.I decided to see what would happen if I took a break.I quit smoking for four years and there was no withdrawl either physical or mental.During the four years I had quit,I would allow myself one week a year to smoke while on vacation.My first time back smoking was great,I enjoyed it like before,crazy low tolerance.One week and I quit just like before.I did notice that during the week I was high as hell off about three good hits.I just didn't seem to enjoy it as much as I used to.I have vacationed for one week a year for the past four years and I just don't seem to derive the same pleasure from it that I used to.I have tried different strains,different quantities and I still just do not have the same feelings I used to.I used to stay high every day and loved it,it didn't interfere with my daily life,no paranoia it just calmed me down and let me look at things different ways.Now,this year I haven't even vacationed,I don't know if I will.The only thing that made a difference for me was last time a buddy of mine gave me a dozen cookies made from great sativa butter and they were outstanding.I smoked the same product with a different outcome,loads of difference.I think I just don't enjoy it like I used to because now I am older and have much more responsibility.I don't know why it's happened but it sucks and I think I am about done with weed altogether.It's too bad there is nothing to take its place!