Jesus teaches in Mark 11:22-25 the keys to having answered prayer.
Jesus replied, “Have faith in God [constantly]. I assure you and most solemnly say to you, whoever says to this mountain, ‘Be lifted up and thrown into the sea!’ and does not doubt in his heart [in God’s unlimited power], but believes that what he says is going to take place, it will be done for him [in accordance with God’s will]. For this reason I am telling you, whatever things you ask for in prayer [in accordance with God’s will], believe [with confident trust] that you have received them, and they will be given to you. Whenever you stand praying, if you have anything against anyone, forgive him [drop the issue, let it go], so that your Father who is in heaven will also forgive you your transgressions and wrongdoings [against Him and others]. (Amplified)