Whatever is not from faith is sin.
Romans 14:23
Faith is hard work. When the external evidence points to failure and hopelessness, it's tough to pray for success and triumph. But as my Grandma says, "When you fail to ask, you fail to give God an opportunity to work." Too many times, I fail to make an opportunity for God because I think I already know what's going to happen (and not especially optimistically). I expect things to go a certain way, and even if I pray words of hope, I don't believe them in my heart. And all too often, things turn out as poorly as I expect, further reinforcing my poor expectations.
Expecting less than the best is really a demonstration of low expectations of God's ability. He is able to do great things beyond our highest imaginings, so why not dream big? Is the sorry return on our prayers just God giving us what we asked for? By asking so little, we may spare ourselves the risk of getting our hopes up, but at the same time we offend the Almighty King of the universe by judging Him incapable of better things. He is all-knowing, all-powerful, and all good, no matter what we may think of the circumstances. God, grant us the faith to honor You with expectation of Your greatness!