Faith is being sure of what we hope for and certain of what we do not see. Hebrews 11:1
For me this means that when I look at a situation that I feel is hopeless, or that I am struggling to see the hope in; a friend who is dying, a child who is on the wrong path, a spouse who is struggling with debilitating sin, I can be sure, God is at work. I can be certain that even when I see nothing, something is happening. Because my faith is in someone who is so much greater than the sum of all human knowledge, I'm not going to "get" it. I'm not. Trying to is ego at work. Being certain and being sure is what that faith entails.
It's not so much a choice as a revelation. It's not so much that I have to choose to believe what I don't see, it's that it's there, and I can put my trust in it even though I don't see it. I know it's there. God has proven Himself to be faithful and true many times in my life. Why would He stop now? That's not what His Word says He will do. His word says that He who began a good work in me is faithful to complete it. (Phil 1:6). My part is to remember the facts, not worry about the faith. Faith is a gift of God. He gives it freely, He wants us to be able to embrace the Truths He teaches so that we can enjoy both a fulfilling life here on Earth and then an eternity of joy in Heaven. It's the facts, having begun in the Spirit are we now being completed by the flesh? Of course not.
When I accepted Jesus as my Redeemer, when I recognized my sorry state as a slave for sale in need of a new Master, One who would not just use me for His pleasure, but care for me, protect me, lead me, I was purchased by the blood of Christ, not something corruptible or unstable in it's value. Jesus Blood payed for my soul. (1Pet 1:18-19) His Spirit began a work of sanctification in my life, changing my behavior, by changing my understanding of how things are. That wasn't done by any feat or reasoning ability of man. It was the revelation of Jesus by His own Spirit that began this amazing journey in my life. He taught me that I could rely on God, I could trust in His Word. I, who I am, who I will be in eternity, my true self, began with the instruction of the Holy Spirit in my life. How could I possibly be completed by any means of myself?
Faith is being sure that God cares about the hopeless seeming situations in my life and certain He is at work in them even when I don't see that work. I will and it's always worth the wait.