Often gratitude for something only comes when there is an absence of it, or when we receive something needed in dire circumstances. But it needn't always be so. What if we were to imagine waking up one day when the sun didn't rise? How many days go by that we don't even think how grateful we are for this, until all at once, it isn't there anymore. Likewise, imagine being without loved ones, and I don't mean only the hard times, but all the happy times that come with them too. How much more grateful would we be if we realized how great our life is for every little thing that we have. We truly have so much to be grateful for!
I have found through my own experience, when I feel that gratitude deep within, it seems like there is nothing that goes wrong. I guess it is something like positive thinking, yet it is so much more than positive. It seems that happiness is just an inevitable side effect of gratitude. Sounds good to me all around.