Personally, I'm convinced that most of our mistakes in prayer come from not understanding what it does, what it's there for. Prayer's first benefit is to the prayer. It's purpose is so that we will "draw near" to God. The ultimate answer to our prayers is to be satisfied, not in the answer, but in the Answerer.
In this way, if the child we pray for never is converted, or our spouse dies of the cancer, in pain, in short if our prayers do not receive the response we hoped for, we understand that the decreed purpose for the prayer was still met: I, the prayer, drew near to God; and according to his promise, he drew near to me.
Of course, the God who tells us he delights to work through means--principally through prayers of his people--will evidently answer many of those prayers even more than we asked or imagined. He is the heavenly FATHER. We fathers understand this relation through our reactions to our own children's cries. Don't you want to be "childish" in this sense? James says to "ask for wisdom." (1:5)
And I'll go one step further, and offer the reminder that we should not expect God to do anything that he has promised to do in response to our prayers if we DON'T pray. NOT praying is a faithless act. "That man should not believe he will receive anything from the Lord." (James 1:7)
Sometimes we need to stop being "strong" and rejoice in our "juvenile" relation to the Father.