Fasting is never required and can utilize many different human wants and needs. Generally, fasting is withholding/abstaining from some physical thing for a period of time with the purpose of using that time and longing for that thing to focus on God and His provision. Most often fasting involves food, but if one is physically unable to do so can involve other physical things.
Remember fasting in itself doesn’t move the hand or heart of God, fasting is intentionally stopping something to help you focus on God, His provision, and His will.
Choose a season of your life to fast. For many this is done around Lent for 40 days, but also includes other seasons of life.
Many choose to fast on a regular basis. For example choosing to fast on Sunday mornings until after worship, choosing to fast leading up to your group meeting, and/or choosing to fast one day or part of a day each week.
There are certain moments in life that seem more critical. In the bible we are encouraged to fast when seeking healing. You may choose to fast prior to a big test, or big day, or when making a critical choice.