A Necessity
It was absolutely necessary that Jesus, as the Lamb of God (John 1:29), live a sinless life on earth so that he could be the perfect sacrifice for all sin. Although he was given God's spirit without measure (John 3:34), Jesus' task of living a perfect existence was anything but easy!
Jesus possessed, by virtue of his mother Mary, the same human nature each person automatically receives when they are conceived. This is because it was determined, in the ages past, that the Savior of mankind learn through experience what it was like to be tempted so that he could more perfectly empathize with us.
Therefore, since the children are partakers of flesh and blood (and human nature), in like manner He also took part in the same . . .
For because He Himself has suffered, having been tempted in like manner, He is able to help those who are being tempted . . . For we do not have a high priest who cannot empathize with our weaknesses, but One Who was tempted in all things according to the likeness of our own temptations; yet He was without sin (Hebrews 2:14, 18, 4:15, HBFV).
Jesus, according to the Bible, implemented a three-fold plan to overcome the chance, though small, that his human nature would lead him to sin in thought or in deed. The stakes were never higher as His sinless life and sacrifical death was the cornerstone of God's plan of salvation for the entire universe!
Imitate the Father
Jesus understood that, while dwelling in a human body, he was constantly susceptible to the subtle, and usually negative, influences of his human nature. He therefore wisely chose to always mimic the judgments and actions of his heavenly Father in order to remain sinless. He did this because the Father was spiritually perfect and not tempted whatsoever by sin.
Therefore, Jesus answered and said to them, "Truly, truly I say to you, the Son has no power to do anything of Himself, but only what He sees the Father do. For whatever He does, these things the Son also does in the same manner . . .
"I have no power to do anything of Myself; but as I hear, I judge; and My judgment is just because I do not seek My own will but the will of the Father, Who sent Me." (John 5:19, 30, HBFV).
Fasting
Jesus, at the start of his ministry, had to endure the direct and concentrated temptations of the devil for 40 days (Matthew 4, Luke 4). He fasted during this period in order to combat the onslaught of subtle deception thrown at him for the express purpose of getting him to sin. Fasting lessened the influence of his human nature upon his choices. It also enhanced his ability to draw closer to God.
Prayer
Jesus prayed many times during his physical sojourn on planet earth in order to remain sinless. His heartfelt petitions, full of sadness and tears, sought out God's wisdom and spiritual strength to endure and overcome whatever came his way.
Who, in the days of His flesh, offered up both prayers and supplications with strong crying and tears to Him Who was able to save Him from death (the second death should he have sinned), and was heard because He feared God (Hebrews 5:7, HBFV).
The quintessential example of Jesus praying for help in his struggle against sin was in the Garden of Gethsemane (Matthew 26:36 - 44). As his suffering drew near he prayed so intensely for three hours that his sweat was like blood and an angel was sent to encourage him.
Then an angel from heaven appeared to Him (Jesus), strengthening Him. And being in agony, He prayed more earnestly. And His sweat became as great drops of blood falling down to the ground (Luke 22:43 - 44).
It was through imitating God the Father, fasting and prayer that Jesus was able to live a sinless life.