And Jesus went forth, and saw a great multitude, and was moved with compassion toward them, and he healed their sick.  (Mt. 14:14)

God does not afflict His children with sickness.  If a natural father were to do such a thing they would be arrested for child abuse and thrown in jail.  For some reason there are those who think that God makes His children sick, or allows them to be sick and it should be called a blessing.  No.  God's will and God's heart can be seen in Jesus who healed all who came to Him.  There is no account of Jesus ever making someone sick in the New Testament 'for His glory.'  There is no account of Jesus ever leaving someone sick 'to teach them something.'  There is no account of Jesus ever refusing to heal someone who came to Him.  Jesus came to destroy the works of the enemy (1 Jn. 3:8) and went about healing all who were oppressed of the devil for God was with Him (Acts 10:38).

God perfects us through His Word (2 Tim. 3:16-17).  He does not need sickness to perfect His children.  He placed all sickness on Jesus.  It would be unjust for Him to place it on you.  He no more uses sickness to perfect us than He would use sin.  He went to the cross to deliver us from both sin and sickness.