When we obey the Lord, our blessings are so great that there is not enough room to receive them (and perhaps this is why they are stored in heaven, too). It is always in our best interest to serve the Lord.
The people that Jesus healed were already good, spiritual people, for after their healing they praised and worshiped God.
Also, I believe that in every instance that Jesus healed someone, that there would have been an accompanying lesson that went with it.