I have tried fasting a few times in my life and always found it helpful. Once, after a fast for a week or so, I was so hungry for food that I went out and bought a pizza. I was sick that night. Not a good idea to introduce pizza to a starving stomach too quickly. Are you hungry enough?
I was thinking yesterday that so far in Matthew 5 it seems to me that the first Beatitude is like a heading for the rest. It all speaks of being hungry for the things of God. "Blessed are the poor in spirit" is the key verse and the rest are subheadings. The "poor in spirit" ie those who acknowledge their spiritual need, are people who "mourn" over their sin, who have the quiet, self controlled strength of being "gentle" and who also "hunger and thirst for righteousness". So Jesus appears to be teaching a succession of character qualities that He sees as important for a disciple. This is leadership training 101 on the mountain.