Our fight against our fallen flesh, the world, and the devil will not end until we are resurrected in newness of life. Sin is basically disobeying God's will. A good pray throughout the day would be: "Father, through Jesus' strength, help me to deny my will and to do Thy will in this moment." (See Matthew 26:42, 2 Corinthians 12:10.) Then we look to see what God would have us do or say next. After we have accomplished this one, little task obediently, we may feel a little happier and closer to God. So, we look to determine the next right thing to do. Our walk is built on one little step of obedience followed by the next and the next. Luke 16:10, "One who is faithful in a very little is also faithful in much."
When we become distracted, we let go of Jesus' hand and walk after our own wills. We lose that close communion with God. This is backsliding. It can be a little slip or a larger fall. But we remember, "Though a righteous person falls seven times, he will get up," Proverbs 24:16. ("Seven" represents repeated falls and is not literal.) 1 John 1:9 teaches us how to recover: "If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness."
The Apostle Paul exhorts us to "work out your own salvation with fear and trembling; for it is God who works in you both to will and to do His good pleasure," Philippians 2:12, 13. This teaches us to be very, very careful to obey God. But, since we battle against sin within and without, we desperately need God's help. Therefore, we ask God to help us to will, to desire, to love His will. Then we humbly pray for help to do it. God will teach us through little steps of obedience.
Fasting is nowhere commanded in the New Testament. Some find it helpful to occasionally deny the flesh through fasting or a restricted diet. They find it aids in restraining their sinful, fleshly urges. However, it is not necessary to do so weekly according to a schedule. A person should fast when he believes it would help him during especially urgent or trying circumstances. Daniel 9:3, "So I turned to the Lord God and pleaded with him in prayer and fasting."