One of my fellow bloggers has put out a general inquiry on behalf of her brother, who is currently serving an LDS mission somewhere out there in the big wide world. It's kind of rare that I actually get asked to share my mission stories/wisdom, so obviously I have to answer the call:
Mission: Illinois Chicago
My favorite part of serving a mission was: Wandering freely day-to-day in places I would never feel safe visiting as non-missionary, interacting with people and characters I would never approach as a non-missionary.
The hardest part of my mission while I was out in the field was: Dinner appointments. Seriously, it's sad. I was a notoriously picky eater pre-mission.*
I overcame this hardship by: I sucked it up (no pun intended) and ate whatever was put in front of me. I also found that with a little practice, often you can transfer food from your chosen utensil to the back of your throat without letting it touch your tongue. Of course, there is still the issue of choking, but if you make sure to cut your food into small manageable bites beforehand, this shouldn't be a problem. When in doubt, apply generous hot sauce. That way, if you accidentally taste bad food, people will assume you are yakking because you used too much Tobasco.
My one piece of advice to a missionary is: Live in the now. You are doing something that is extremely cool (both in a spiritual and a secular, "I can't believe I am riding my bike through the ghetto and shooting the bull with crack dealers" sense) that you will never be able to experience again. And no, it will not be the same with your wife when you go out as a couple in fifty years. Plus, life as an RM is not nearly as idyllic as people might have you believe. Enjoy the opportunity you have to focus on a single worthwhile subject (helping people find meaningful happiness in this life and the next) instead of worrying about a whole lot of irrelevant rubbish (the outcome of "American Idol").
*Offended parties can direct all complaints to firstname.lastname@example.org. Really. I'm not blowing you off. It's a real address.