God is our faithful Father.
He gives only good things to His children.
"Every good gift and every perfect gift is from above, and comes down from the Father of lights, with whom there is no variation or shadow of turning."
James 1:17
"Or what man is there among you who, if his son asks for bread, will give him a stone?
Or if he asks for a fish, will he give him a serpent?
If you then, being evil, know how to give good gifts to your children, how much more will your Father who is in heaven give good things to those who ask Him!
Matthew 7:9-11
Our Father who is in heaven will give good things to His children, but He gives them to thoses who ask.
That's how we appropriate the good things of God.
When we ask, we are to ask in faith, expecting to receive only good things from God.
He will not give us something that looks good, but is really evil or bad.
Healing is a good thing; sickness is a bad thing.
When praying for healing, expect healing; don't expect sickness to remain.