“Were you to ask, ‘what are the means of overcoming temptations’, I would answer: The first means is prayer; the second is prayer; the third is prayer; and should you ask me, a thousand times, I would repeat the same.” St. Alphonsus Liguori 

Why would this saint emphasize prayer as the greatest tool to overcome temptations? What is the purpose of temptations? The Devil wants to separate us from God? What is the purpose of prayer? It focuses us on the Lord. If our focus is on the Lord, who loves us, then our attention is not on us, which is what temptations try to do. If our heart is directed on praising and thanking the Lord, where then is the power of the temptation?