So many believers assume that God is not willing to heal them, probably because their ill health has persisted for a very long time.
God is always willing to heal. It is His perfect will for you to live in perfect health. That was exactly what Jesus demonstrated with the man that was full of leprosy in Matthew 8:1-3.
God is a good God. Part of the reason why he sent Jesus to die for our sins is so that he can bring us salvation which includes healing: wholeness and soundness.
In 3 John 2, the Bible records that God desires above all things that you prosper and be in health even as your soul prospers. If he wants you to be in perfect health it also implies that he also wants you healed.
Sicknesses and diseases are not of God. They are the works of the devil. Jesus came to destroy this works of the devil as a proof that God wants you to be healed and restored to perfect health.
Jesus healed all manner of sicknesses and diseases during his earthly ministry. In Matthew 4:24-26, the Bible records that he went about preaching the gospel, teaching in the synagogues, and healing the sick.
Jesus has not stopped healing the sick, he is still very much willing to heal you if you would release your faith.
Say this out loud: Thank you father for your provision of healing and perfect health I believe with all of my heart that it is your will for me to be healed and be restored to perfect health.
Therefore in the name of Jesus I command this sickness to leave my body right now. I declare in the name of Jesus that I am healed in my body, cleansed in my blood, and I am made whole in my bones in Jesus name.