I've only ever fasted on Yom Kippur. This year in particular I found the fast exhausting, exhilarating, and cleansing in equal measures. The Yom Kippur fast is a minimum of 25 hours, but it happens only once a year; during Ramadan, the practice of abstaining from food and drink during daylight is repeated all month long. The sustained focus of the practice humbles me -- as do its logistical challenges. I was in Accra during Ramadan a few years ago, and our driver Émile was observing the holiday. I could barely walk ten feet without needing to chug bottled water; I was amazed that he could function, fasting in the heat of the day.
It's my understanding that the fast from food and drink is meant to both represent and spark the desire to improve oneself and live according to God's will. (Sounds familiar: that's what our fast is supposed to do, too.) The doors of heaven are considered to be open during Ramadan, another intriguing commonality between our two holiday conceptions. On Yom Kippur, Jewish tradition teaches, the gates of heaven are opened; the final service of the holiday, ne'ilah, represents the time when the gates are closing.
Last year at this season I remember really enjoying Jesse Maceo Vega-Frey's Hunger is God's Food, an essay exploring one guy's decision to observe Ramadan and his process of self-discovery during the month. (It's really excellent. I recommend it.) And this year I've just read Faiza Saleh Ambah's Enough Faith to Fast, also good.
I wish my Muslim readers a Ramadan mubarak! May your observance be fruitful. I'll be thinking of you as the Heshvan/Ramadan moon waxes and wanes.