Prayer - pleasure or duty?

The other Sunday around 4pm Josie and I had this discussion around who was going to deeper prayer, which is basically the one prayer meeting our church has each month. To be honest it was one of those polite stand offs where suddenly we both felt a calling to put the kids to bed. In the end I got what felt at the time like the short straw even though deep down my spirit knew it wasn't the short one my soul was convinced of it. I even said to my brother who doesn't believe in God that I was going out of obligation. Those words kind of got stuck in my throat and I felt bad for saying them never mind thinking them. So the question this raises is why is this the case? Fact - I've never come home from a prayer meeting wishing I hadn't gone. Fact - Ive always been glad I've gone at times über glad. You could say ecstatic. Fact - I always feel better for having gone. So if all of that is true, which I know it is, why do I and no doubt many others wrestle with it so much? You would think that if something is that good, it would be a no-brainer, yet still there is a battle. My biggest struggle in my walk with God is moving from that place of duty to pleasure in my prayer life. I so often pray because I should and not because of the sheer joy I experience. I've read the books, listened to the talks, tried all sorts. I guess for now I just have to hope that my spirit wins more times than my soul!