James 5: 16b - The heartfelt and persistent prayer of a righteous man (believer) can accomplish much [when put into action and made effective by God—it is dynamic and can have tremendous power].
A man of God once said publicly that God always answers prayers. He was challenged by those who heard him that how come so many people have not received answers to their prayers, he simply told them that it's because most people are lazy in the place of prayer.
In James 5:16b we see some of the atoms of prayers that make impact. A heart felt prayer is one which the person praying believes in the deeper most part of his/her being that the solution to his/her problem can only come from God.
Hence when he/she has prayed once, twice or thrice and he hasn't seen the desired result, he/she does not lose hope. They continue in prayer persistently (continuously, constantly, always). You are not asking for the same thing several times because you doubt if he heard you the first time, rather you are persistent because you believe that He is the only one who can help you.
This kind of prayer can "accomplish much", another version says it "makes many things available". What are the things you have been asking God for and the answers seem not to be coming, please don't lose hope.
Keep asking, keep seeking and keep knocking. Make prayer a vital part of who you are and ALL THINGS WILL BE MADE AVAILABLE UNTO YOU.