I've noticed something. If I skip my time with God, for several days in a row (okay, so even just one day), and I go to serve in KidBUILDERs, or somewhere else, I am so miserable and I have no patience when I serve. It's usually not only because I skipped my time with God. but because, as a result of skipping my time with God, my heart isn't right with him.
When I do spend time with my Jesus, my attitude is so much better about serving. I think this is because my heart is right with God so I can pour HIS life into others. I have something to give. Whereas, if I haven't been spending time with him, I have nothing left to pour into anyone else, because I've had nothing poured into me by God.