Each day I go to the gym, I'm reminded why I don't like to exercise! For some reason, running on a treadmill, sweating on the elliptical trainer, or lifting weights isn't how I like to spend an hour of my day. But, exercise increases my muscles and my health.
I don't know why God allows problems to arise in our life, but I think He intends to use them to deepen our faith and mature us. Trials and troubles are like dumbbells and treadmills for our soul. They make us stronger. Even the Israelites realized this at the end of Exodus 14 when it said they "believed the Lord and His servant Moses." Faith is when we fully rely on God.
In Luke 1:45, we read where Mary learned she was be the earthly mother of Jesus. Her relative Elizabeth said, "Blessed is she who has believed that what the Lord has said to her will be accomplished!"
In Romans 4:20-21 it says Abraham "was strengthened in his faith and gave glory to God, being fully persuaded that God had power to do what he had promised."
Even Paul told his friends in Acts 27:43-45 during the storm to "Keep up your courage, men, for I have faith in God that it will happen just as God told me."
I note how someone sits in a chair next to me and that chair hold them up. They can put all of their weight on the chair and it holds them. They have faith in the chair's strength and I can, too. When I turn on the shower, I have faith hot water will flow. God created this world so that the principal of faith is always at work.
For Christians, faith is assuming God is in control and He will care for us, based on scriptural promises. We may not understand every turn of event in our life or have the forethought to appreciate why God is allowing it to happen. But God has given us promises and we disappoint Him when we question His ability to keep His Word.