>>481921I have hiked a 1,000 mile long section of the Appalachian Trail in spring of 2014. I did train to some extent before going, but not too much. It worked out all right, I was one of the medium to fast hikers. I started out with a little too much (for me) gear (total pack weight on day 1: 35 pounds), but reduced that over the course of the hike (bounce box etc) to 26 pounds. One of my best buddies who was around the same speed as me had a pack of no less than 45 pounds at any given time. Lesson: Carry whatever you want to carry. High comfort level? Carry much. Low comfort level? Don't carry much. In the 70s and 80s, thru-hikers had to carry 60-70 pounds, and they too could do it.
Most important gear: Shelter, sleeping stuff and an emergency whistle. And obviously your shoes. They must fit you, you must love them. You can go trail runner, you can go hiking boots, whatever you like - it's all a matter of preference. You're the boss of your hike, no one else is.
How to train: Do a hike of 3-5 days. Test your gear: Does everything work as intended? Test with rain and light snow: Still everything ok? Then, do a few of those 3-5 day hikes with only restocking food and fuel. Still everything ok? Then you can do any long distance trail of your choice.
Advice not from article: You can take a pair of woolen socks and use them as gloves. It's enough for gripping your trekking poles. Though it's certainly nicer to have gloves when you cook and stuff because you can't grip your mug with socks!
Also: Take pictures of the people you meet. Especially the AT is a quite social experience (if you want it to be) and the people are usually very awesome. You will want to remember them.