Although you may already be in pretty good shape, adding any type of aerobic exercise to your workout is often a challenging process. If you are not in the best shape and want to start jogging, it may be best for you to start out with a week of distance speed walking. Remember, you have to walk before you can run (but you also have to walk before you can jog).
That said, set a date that you want to start. Get yourself a sports watch to wear that you can use to time your jogs.
The first day, go for a 2 mile speed walk. Set yourself a defined route that you would like to use for your workouts. This will help you out later on.
The next day, go for that same 2 mile speed walk, using the exact same route. This time, make it a goal to cut a minute out of your time. **If your legs are sore, it's okay to take a day off. Resting once in a while is good as well, as it gives your leg muscles time to rebuild and get stronger.**
For days 3-7 continue the pattern. Use the exact same route, and try and cut a minute off of your time each day. By the end of the week you should have cut 7 minutes off of your original time. This might not seem like a lot of time, but when you are talking jogging or running, 7 minutes is a great improvement.
Now that you have been incorporating aerobic exercise into your workouts for a week, you should have a much easier transition into the actual jogging workout. You now also have a good route that you can use when going for your jogs. For week 2, if you are not yet jogging start speeding up your pace a bit. If you find yourself getting tired after 10 minutes of jogging, then walk the next 5 minutes. But be sure to pick up jogging again immediately after the 5 minutes.
By following the same basic concept as your first week, you should eventually be able to transition yourself into a full-time jog/run within the next couple of weeks. Remember to keep track of your times and set goals so that you continue to get faster and faster. The standard of cutting 1 minute off of your time was just to get your started, but once you get a full jog/run down you will not be able to cut off minutes at a time.
Now that you have your original route mastered along with having developed from a speed walk to a jog, you can now change routes. This is always a good idea as it brings more diversity to your workouts so that you do not quickly get bored of them.