1. Jesus never doubted those who followed him would fast. He didn't say if you fast, he said when you fast (Matthew 6:16). Jesus also didn't say "maybe they'll fast, maybe they won't." He said, "they will fast" (Matthew 9:15).
2. We are hungry for more than food. As followers of the Bread of Life, we aren't satisfied by mere physical food. It fills up our bellies but not our souls. First and foremost, we hunger and thirst for Him. We are desperate to "taste and see that the Lord is good" (Psalm 34:8). Fasting from what we can taste and see brings us closer to experiencing the One our souls truly desire.
3. To battle against sin and temptation. Denying ourselves some temporary pleasure builds up spiritual muscles that help us walk more obediently with the Lord. Worldly wisdom would assume us to be less patient and more "on edge" while denying ourselves food. "Hangry" was coined out of that very experience; we can become so hungry we get agitated and angry. The exact opposite happens when fasting. The Fruit of the Spirit become more abundant when fasting. Miraculously, I find myself more patient and gentle with my children when I am fasting.
4. To experience more joy and thankfulness. Fasting is temporary, it has a definite end in sight. When we resume eating, we feel an incredible sense of gratitude for something as simple as breakfast. It's much like enduring sickness. When health returns, we are overcome by the great gift of feeling good again.
5. To humble ourselves: "I humbled myself with fasting" (Psalm 35:13). Pride is one of the biggest stumbling blocks in our relationship with the Lord (and with others). In fasting we elevate our spiritual needs while forcing the physical ones into submission. It's hard to be puffed up with pride when you're battling your flesh.
6. To repent: "On that day they fasted and there they confessed, 'We have sinned against the Lord'" (I Samuel 7:6). Sometimes our great need for forgiveness motivates us to do something—anything—to show our true repentance.
7. For spiritual strength. Jesus fasted 40 days when he had to face the temptations of the Devil. Moses did the same when he waited for the commandments and again when the Israelites needed to turn back to God. Elijah also fasted for 40 days. Fasting for such prolonged periods may weaken the body, but apparently it strengthens the spirit.
8. To be more disciplined. Self-denial is not even a thing anymore. We can get whatever we want, whenever we want it. Fasting reminds us that there are great benefits to be found in any worthwhile discipline, all the more true in spiritual disciplines. Our bodies are temples of the Holy Spirit (I Corinthians 6:19-20); how we treat them matters more than we often care to admit.
9. To rid us from worldly distractions. We're very good at insulating ourselves from pain and discomfort. We seek comfort in food, drink, material things, relationships... But our souls forever long for more. "Christian fasting, at its root, is the hunger of a homesickness for God" (John Piper). Making ourselves temporarily uncomfortable through denial nudges us toward the open arms of our true Comforter.
10. For love and worship. Anna fasted and prayed as a form of love and worship, "she never left the temple but worshiped night and day, fasting and praying." Just as there are times when repentance draws us to fast; a deep love of God and desire to worship more deeply may do the same.