To me, the Lord's reply to Apostle Paul's prayer springs to mind.
In the book of 2 Corinthians 12, Paul was given a thorn in his flesh and the Lord said
"My grace is sufficient for you, for my power is made perfect in weakness"
Paul goes on to say he will boast all the more gladly about his weaknesses, so that Christ's power may rest on him.
Paul was the one who healed many and yet the Lord chose not to heal him.
In this regard, sickness could be interpreted as Lord's calling for you to come nearer to Him.
I encourage you to pray as Paul did; for Christ’s sake, I delight in weaknesses, in insults, in hardships, in persecutions, in difficulties. For when I am weak, then I am strong.