I've been wondering about that for a while. IF God is the greatest most beautiful most perfect loving thing why would it be a command to love him? Wouldn't it just be natural response? Like most people who see a cute baby don't have to be told to think it's beatiful. Maybe (which I'm afraid) God is really a horrible slavemaster monster campared with our human understanding that we have to make the decision to completely alter our view of what is good adn make the decision to love something that is comppletely opposed to our natural sense and inclination. This would make sense with the tradional views of Jewish Christian Muslim view of GOd who wants us to be self-sacrificing. It is pretty scary though when you realise that you can't just force yourself and asking God for help is entirely useless. It may just be that we are completely fucked. Those who have a natural love for GOd are the chosen and the rest of us suffer on earth and will continue to suffer for eternity as we blame God for making us fucked up and then not helping us get how we are supposed to be. THe worst part is there is no way we'll ever know and all this speculation is a waste of time.
Some mystics believe that in our most natural state, at a deeper level, everybody on earth loves everybody and everything else. According to this way of looking at it all negative emotions are the result of repressing love in the name of fear. They are in fact love in a twisted, perverted form. Basically the idea is that everyone already loves God. If you're not feeling it then there's something inside you that got twisted somewhere along the way. If you look at it that way then saying "Love God" is just saying "If you don't already love God then you'd do well to look inside yourself and figure out why".
I've had moments like that too. In the middle of those moments you can see what it is that keeps you from feeling that way all the time. For me it's mostly pride.