Handling the Distance
Since the primary activity during trekking is walking, your best form of training is to go out and walk. Ideally, if you build up to walk comfortably under normal conditions the daily, weekly, dare I say monthly mileage of your trek you stand the best chance of success. The key to building up to this mileage is a gradual build up in daily and weekly mileage.
Everyone starts at a different point. One guiding principle is not to increase your weekly mileage by more than 10% per week. Therefore, if you are walking 3 miles 6 days a week and eventually desire to trek 10 miles a day, it takes approximately 14 weeks to build to your trekking distance safely. While this is a conservative estimate, it is one that is very achievable given a dedicated plan. Observe the following chart of mileage increase. Note that the days you walk specific miles or rest can be switched within the week as your schedule permits.
An alternative training schedule follows. It serves two purposes. First, how many of us have schedules consistent enough to train nearly the same amount for 6 days a week? Second, not all treks are consistent in the amount of miles traveled a day. Therefore the alternative training schedule is provided. It provides a five day a week format that contains longer days on the weekend. Ideally, if your schedule permits moving one of the longer days to the middle of the week, do so. It provides your body recovery time from the other long walk of the week. Notice however that although the distance on some days is much greater than previous schedules, the weekly mileage does not increase at a more rapid pace.