How much would happen if we just prayed and did nothing else? Probably a lot more than we can imagine but yet, not everything would happen with prayer alone. There is a battle in the Old Testament which gives us a pretty good clue about the way prayer works.
The Israelites were out in the desert when the Amalekites attacked them. Moses came up with a response plan which directed Joshua to pick fighting men to go to battle against Amalek the next day while he positioned himself on top the mountain above the fight. He would pray and Joshua would engage the enemy.
Exodus 17:11 tells us how things went. "So it came about when Moses held his hand up, that Israel prevailed, and when he let his hand down, Amalek prevailed." Aaron and Hur were with Moses and they supported his hand when it was too heavy to continue.
Moses prayer was successful but so were Joshua's actions. "So Joshua overwhelmed Amalek and his people with the edge of the sword." This verse seems to give Joshua the credit. Actually both actions were integral to success. If it would not have been for the prayer the battle would have been lost, but someone was needed to carry out in the natural what the prayer declared in the supernatural realm.
Prayer and action go hand in hand. For instance, one may pray for souls to be saved while another goes forth witnessing. One prays for provision for a starving country and others arrive with food.
Whether God assigns you to prayer or action, perform your duty humbly with excellence. Your partner is depending on you!