The plain fact about backpacking is that at times it is darn hard work. We convince ourselves that this will be all worth it once we reach our destination of solitude and beauty, and drop this heavy pack off our shoulders. Fortunately, most of the time it is true. Getting in Shape. Walking as much as we can is probably the number one thing we can do to prepare for backpacking.
Long walks are particularly good, especially ones uphill.
I have read that in a normal workday most adults only spend about two minutes outside. Structuring your day so that you can always walk in some natural habitat close to home will not only get you ready for backpacking but will also allows you to see some of the beauty that each day possesses. The only way to prepare your body for carrying a heavy load is by carrying a heavy load. In the weeks before my first backpacking trips I often throw some 25 pound weights in an old pack and climb the steepest hill near my home with the pack. This definitely prepares me for the first trip out.