In God's work, you will often have troubles. If you are actively seeking to take territory from Satan, you will experience opposition. This opposition manifests in different forms. It could come as harrassment from government authorities, as financial challenges, as relational difficulties. It could come through sickness – which can be a form of satanic attack. It can come through people sinning against you.
The Bible says in James 5:13, "Is anyone in trouble? Let him pray". This is one of the greatest secrets to genuine church growth. Churches that have taught and practiced this principle have generally flourished.
God desires that men would call upon His name for help. He desires that people will realise that they cannot make it on their own. So in this sinful, fallen world, God allows trouble to come. God hopes that men will reach out to Him in the midst of their trouble, and in so doing, will begin to discover that God is a merciful, prayer-answering God.
The Korean churches experienced revival through prayer. People were taught to cry out much to God when they had serious troubles. The results were two-fold. On the one side, people got answers to prayer. On the other side, people got to know God. This is exactly what is needed in our times. We need to know God.