Luke 18:27 tells us:
Jesus replied, “What is impossible with man is possible with God.” - Luke 18:27
This verse takes place in the context of Jesus talking to a Rich Young Ruler who was asking him what he must do to inherit eternal life. Jesus, knowing the state of this man's heart, told him to sell everything and follow him because he knew that possessions and riches directed the mans heart and affections.
This actually confused the disciples since a common belief at the time was that because rich people were so prosperous, they were the ones with all of the favor from God. Jesus squished that notion pretty quick. Jesus points out that there isn't anything that man can do to save themselves, but with God, that all changes.
I want you to know that if you're dealing with sickness in your life or a situation that just seems impossible, remember that what is impossible with man is possible with God. Does it necessarily mean that God will change your circumstances? No. But we can know that truly everything we're going through is in God's control.