When we look at the two possible meanings, we need to find the onus - who is responsible for bringing Paul to where He is when he is writing this letter.
The verse makes it very easy. There are only two who are mentioned in the passage - Paul and Jesus, the Son of God.
So, Paul, or I (or you) are responsible for our faith in Christ and if we can find enough faith, believe hard enough, then we can have a successful Christian life and live in Jesus' love and sacrifice and our Christian lives will forever be tied up in our own limitations. I will forever be going around telling myself, "If only I could believe a little more," and punishing myself for not having been able to do so. I know that some teach that faith is an act of the will, but have you ever tried to increase your faith by a sheer act of your will? Doesn't work very well, does it? Well, at least not for me. But, where do I find more faith? Read the Bible more? Yes, but it depends on where you read and what you are searching for when you read.
Have you ever tried quoting Bible verses back to God to try to get Him to do what you want? That doesn't work very well either, most of the time. When it does it is because your heart has become His heart in the matter at hand.
No, living by the faith of the Son of God is what is required. Asking the question, "What did Jesus believe about the things before me?," then getting behind what He believed. Jesus said, "If you abide in me, and my words abide in you, you shall ask what you will, and it shall be done unto you. " If that's not working for you, it is because His words have not yet come to abide in you. You may say you know the words "by heart," when you have merely memorized them. More...