If you recognize the many of benefits of running you'll be asking yourself “why don't I run?”. Running is a fantastic addition to your fitness.
“One run can take you many places.”
Running has many advantages, but can be harmful if not done properly! Running with proper form allows your body to take full advantage of its spring and elasticity, which is why I distinctly prefer running to walking. However, when trying to run faster, dedicated runners can get very tight, which can lead to injuries. It bothers me when I hear about runners who had to stop running because they hurt themselves (notably the knees, but also the back, feet, shins, etc).
My method of running does not put any extra stress on the body because it is not concentrating on speed. Assume the body-attitude of running while you're walking (walk as if you were running at a slower pace). Once you've warmed up, you can increase the pace to move from walking to running. As you tire or start climbing a steep hill, the pace can be slowed back to a walk while maintaining the body-attitude of running.
Now, go out and run!