thats a very ubiquitous phenomenon. i think it means that the reasons that made you start smoking in the first place no longer apply. let's say, you started smoking for the benefit of socializing more easily, but now you realize that weed can't really help you there/you learned all you can from its social powers.
when a sick person takes their medicine, they heal. when a healthy person takes said medicine they experience side-effects as if their body is telling them to stop taking what they're taking. and taking drugs is ultimately a form of self-medication.
i can relate from experience that during my prime moods, i enjoy weed the least.
maybe you should just take a break from it totally for a couple of months, and then try again. if that doesn't change it for you, it would be my observation that you have no buisness to do with cannabis. don't worry, there are plenty of other ways to enjoy life.