Regardless of how many kilometers you hope to hike per day; it is important to prepare your body physically. The best way is to load up your pack and get out and backpack. The more rugged the terrain the better. However, we know that is not always an option. If you have access to a gym then get on the stairclimber and do some work with free weights. It is important to get your body conditioned for long hikes on changing terrain.
It is also wise to have some experience with the gear you will actually use on the hike. Get comfortable with a new pack and make sure your shoes are broken in. Pay special attention to boot fit and how your feet feel as you take practice hikes. It is better to trouble shoot blister issues before you start any long hike. For any question you might have please login to the forum.