While, I don't expect to see many people in ashes and dung these days -- nor fasting for up through three days, I do think there is much to learn from such examples. While the "missions" in my life aren't anywhere near as challenging as that of Esther, still, they are uniquely my own that God has given me and have oftentimes required getting over a fear, asking the Holy Spirit for "just the right words" and asking for a special grace to fulfill what is necessary. There are missions in my life that I will fast, mortify and pray in earnest for; I'm sure I'm not alone.
Here are some thoughts from Fr. Francis Fernandez (In Conversation with God, Lenten volume) with more scriptural references in regard to fasting:
"....Fasting .....one more sign of the spirit of penance that God asks of man. In the Old Testament we can find gradually developing with ever increasing richness, the religious sense of penance, as a personal religious act, which has as its end love for and abandoment in God. [Paul VI, Apostolic Constitution, Paenitemini, 17 Feb, 1966] When it is accompanied by prayer it can be used to manifest humility before God. [Lev 16:29-31) The man who fasts turns toward God in an attitude of total dependence and abandonment. In Holy Scripture we see how fasting and other works of penance were performed before the commencement of any difficult task [Jude 20:26, Esther 4:16], to implore forgiveness for sin [1 Kings21:27], to obtain the cessation of a calamity [Jude 4:9-13], to gain the grace needed for the fulfillment of a mission [Acts 13:2], and to prepare oneself to come face to face with God [Ex 34:38, Dan 9:3]."
Lord on the day I called for help, you answered me....(Psalm 138)