How You Spend Your Time While Fasting is a Personal Decision
My ideas about fasting were shaped more by the world and what I saw in the media than by God's Word. So I grew up with the idea that fasting was something done by cloistered monks in prayer cells, hermits in caves, and very spiritual people on sacred retreats. But that's not the way the Bible thinks about fasting. In the Bible, fasting often occurs as something you do while carrying on your everyday activities!
Matthew 6:16-18 demonstrates this, since Jesus pictures a situation in which Christians are among other people going about their normal duties and activities. In fact, soldiers involved in the activity of warfare sometimes fasted (1 Samuel 14:24) as well as the sailors on the ship with Paul (Acts 27:33). There is a certain sense in which fasting, even in the midst of your daily activities, becomes a constant prayer to the Lord. And in the actual experience of fasting, a periodic pang of hunger can become a good reminder to send up a short "arrow prayer" for the particular thing about which you are fasting.
What a marvelous freedom God gives us in the area of fasting. Jesus assumes that we will fast, yet he leaves the choice of when to fast, the length of our fast, and the decision of how we will spend our time while fasting completely up to us!
Fasting Does Not Negate Our Responsibility to be Obedient to God
We cannot fast and pray expecting God to bless when there is known sin in our lives. Fasting does not impress God with our spirituality to the point that he ignores our disobedience. On the contrary, genuine fasting will always cause us to examine our hearts to make sure everything is right with Him.
The people of Isaiah's day thought that they could fast in disobedience and God would hear them. But God said, "on the day of your fasting, you do as you please and exploit all your workers. Your fasting ends in quarreling and strife and in striking each other with wicked fists. You cannot fast as you do today and expect your voice to be heard on high". (Isaiah 58:3b-4).
Wealth is not just what you have, but what you are.