The hardest part about keeping the Ramadan fast for me was fixing my sleep schedule. It felt like cheating to me if I woke up at 5 to eat, then went back to sleep until noon, and got to eat again at 5:30 or 6 or whenever sundown was.

Also, the Ramadan fast requires no smoking, no liquids (so no water which makes exercise hard), no sex, no music, and a whole pile of other restrictions depending on which imam you listen to (like, my father's imam says no t.v. or talk radio either, and when I was in middle school, books read purely for pleasure were also forbidden).