Trusting God can be one of the most easiest and hardest thing in my walk with Him.
I hear it in various forms: "Put your trust in God", "Surrender your all to Him", "God is in control and have faith in Him", etc.
In the Christian circle, it is an often-used cliché to encourage a brother or a sister who is struggling for a breakthrough, or has had a major disappointment or setback in life.