Hiking more, and with more weight. What ecarter1 said at the beggining is bang on. Obviously don't build up too quickly, and scale back quickly if things hurt too much.
Any endurance training scheme needs needs a solid dose of motivation, because it takes a lot of time. Some people are motivated by hiking, some by biking, some by skiing, and there's probably a few special people who can put up with doing a stairmaster for several hours, but I've never met any. Figure out what you like, and make that work for you.
The natives and european immigrants who used to trek these lands without the help of cars and roads didn't eat anything special, and they sure as hell didn't use any suppliment pills. If you're a healthy individual, your body just needs regular food (that's why those bottles have fine print to the effect "This product is not approved for any particular use" or something like that). If you think you need supplements, you should probably see a doctor, because that might suggest an underlying health problem.
Last edited by trick; 02-12-2019 at 06:18 AM.