What kind of training did you do?
I left for my trip on March 21st, and started training for it on December 31st. My first step was to head to REI and get myself a great pair of hiking boots. Every Sunday was my hiking day. I would hike between three and six miles on local trails to get used to my boots, hiking in general and breaking them in.
Around the end of January, I bought myself nice backpack for my trip. I would fill my backpack with a good 30 to 40 pounds of gear and wear it around the house when doing chores and hiking as well. I did this to get used to the fit and weight of the stuff I would be carrying. Even though I ended up using a porter for some of my gear, it was helpful to carry it around loaded with phone books, weights and clothes. I also bought some 5 pound ankle weights that I would occasionally wear while out hiking ahead of my trip.
Later I got some hiking poles and would purposely practice hiking off the trail in deep snow up to my knees with a full backpack to try and prepare myself for whatever I might encounter when in the mountains. The hills by me are small, only an altitude change of around 100 feet or so, but I would hike up them carrying all of my gear in the deep snow eight to ten times. It's a lot harder than it sounds and definitely tires you out.
It's also important to test out the clothes that you plan to wear on the trip. A couple of weeks before I left, I headed out and bought all of my synthetic fabric clothing. I made sure break it in out on my local trails to see how well it worked in keeping me warm as well as how comfortable it was to wear.
What about working out in the gym?
I also tried to work out in the gym as well. I would lift weights and ride the cardio equipment. I tried to work out five or six days per week to make sure I was in good shape to handle the altitude, since I had never been that high. When lifting weights, I focused extra effort on my legs to try and build up my leg muscles for all of the hiking I was going to be doing.
About four weeks before my trip, I started tapering my workouts in the gym off, and stopped running. Cardio was done by swimming laps in the pool. I basically didn't want to do any exercise that might result in me twisting an ankle shortly before my trip. I still made sure that I hiked every Sunday though.
You don't need to look like a bodybuilder to do the hike. On the other hand, don't expect to pick yourself right up off the couch and have a bunch of success either. Start by breaking in your gear that you're going to use on the hike and make sure you get some other good fitness time in, to give yourself the best chance of success on the hike.