To fast means to give up something for a time (like food, video games, dessert, etc.). Many Christians fast during Lent (the 40 days where we remember how Jesus fasted in the desert), but you can fast whenever you want for as long as you want. Biblical fasting is not about losing weight or looking "holy" to your friends. And it's not something that you can do to "get out of" doing what's right. Fasting is a way to reconnect with God and reset our priorities!