Taking my three year old to school today he says "why is it cold in the car?". I told him because it was cool outside and asked if he'd like me to make it warmer. He said "you're going to make it warmer outside?". I laughed and told him that God controls that but that I can make it warmer in the car. He says, "ooh, so God controls the temperature outside and you control the temperature inside".
I felt a moment of revelation as I realized what a profound spiritual word that was. So many times we wait in our spiritual "cars" as outside it heats up or chills down and complain about being hot or cold. We wait and pray for what we perceive are perfect conditions outside so that our circumstances can keep our internal emotions at the perfect temperature. Not too hot. Not too cold.
Jesus warns about being lukewarm and only going to the comfortable places. There is not a person in biblical history that was called to a comfortable place. But just as it's God's promise to tame the spiritual "weather" around us, it's OUR job to control our internal weather by keeping our thoughts fixed on Him instead of craving the absence of spiritual challenges in a world in which we are forcefully advancing the kingdom of God.