Three miles is nothing to a track star, but if you are a running novice, the distance may seem insurmountable. If you are an otherwise healthy person, you can run three miles if you commit to consistent training. Start with a short distance and work your way up to longer runs. Consider registering for a 5K race -- just over three miles -- so you can work toward a goal.
Invest in proper shoes. You don't have to spend money on fancy gym clothes, but a good pair of running shoes is an essential part of injury prevention. Visit a sporting goods store and ask a salesperson to help you select running-specific shoes with a good fit and proper support.
Make a plan. In order to get in shape, you'll have to commit to a workout most days of the week. Look for openings in your daily schedule. If necessary, get up an hour early so you'll have time to run.
Start with intervals. If you are new to fitness, you probably won't be able to run a full three miles. Instead, begin by cycling through running and walking intervals. Since you have a goal of three miles, use distances instead of times. For example, you might start by running 200 yards, then walking 200 yards, running 400 yards and walking 400 yards -- and then repeat the cycle twice.
Take it slowly. It may take months before you are able to run three miles without stopping or walking. Going too far too fast puts you at risk of injury. Increase your distance by a quarter of a mile each week and gradually decrease your walking interval. For example, you might complete six cycles of quarter-mile runs and quarter-mile walks with each workout for one week. The following week, do a quarter mile of running and walking, then do two half-mile runs broken up by quarter-mile walks.
Be consistent. Plan to run five or six times a week even if you don't do a full three miles with each workout.