When we are obedient to the word of God our faith is increased. We must trust that God's word never changes and what He says he will do, He will do.
The lepers were unclean, they were outcast from society, and they were taken from their families and homes forced to live in solitude. When the lepers saw Jesus they cried out "have mercy on us." What they were really saying was Lord have pity on us, we need you to do a work in our lives.
We must come to the realization that we need Jesus. We can do nothing without God. I'm sure that after Jesus healed the lepers their faith was increased. Think about it, if God has healed you, or a family member, if God has provided you with a job, or whatever God may have done for you that no one else could, your faith is increased.
You faith beforehand may have been on empty so to say, but once God works the miraculous your "gas tank" of faith is on full! We must trust God in every situation that He will work it for our good. If your faith is on empty, if it seems like nothing is gonna work out for you, just remember the words of Jesus. If we would but have the faith of a mustard seed we can move mountains! Lord increase our faith.
Rev. Mark Denard