I also drink a pot of coffee in the morning. I don't really notice any mood changes with it, whether I drink it or not.

However, I know that everytime I try to quit smoking, it makes me extremely manic, to the point where my gf asks if she can go buy me a pack.

I know my habits are bad, but I don't care. Like you said, they're enjoyable.

I don't see why you have to give them up if you don't want to, but that's just me, I 'spose.