As I was thinking more about what I shared in the last post, I ran across another helpful insight into my prayer life.
Paul uses a verb form in the prayers of verse 5 (May God grant you) and verse 13 (May God fill you) that really functions as "an appeal to the will" of God. Wallace says that this request is a "polite request without a hint of doubting what the response will be." While the verb form itself may indicate a request or prayer is merely a possibility, because we know who God is, and what He is like, that possibility becomes a reasonable expectation and something worth setting our hope on.
Imagine what that meant to Paul. Imagine what that means to you when you pray these types of prayer.
Wallace goes on to say that "prayers offered to the semi-gods of Athens could expect to be haggled over, rebuffed, and left unanswered. But the God of the NT was bigger than that. The prayers offered to him depend on his sovereignty and goodness. If uncertainty is part of the package, it is not due to questions of God's ability, but simply to the petitioner's humility before the transcendent one."
So, we can approach God with confidence asking Him to fill us with joy and peace, and for Him to grant us endurance and encouragement. We can know we are not trying to force his reluctant hand to act on our behalf. He is gracious and glad to give good gifts to His children who ask for them.