There’s no shortcut to magically being able to run farther. You have to get out there and put in the miles. You will need to start running longer distances and run fairly often. You should be running 4-5 times a week if you want to build up mileage. However, you only want to add 10% to your weekly mileage from one week to the next. For instance, if you are running 10 miles this week, you want to be running 11 miles next week. Doing it this way will keep you increasing mileage safely without getting injured.
A couple days a week you should be doing tempo runs. What this means is that you will run for a few minutes at a faster pace than you usually do, then run slower to recover. You do this over and over until you have completed the distance you wanted to cover. In the beginning, you may only do a couple of these speed bursts – and that’s OK. Just add one more to them every week. I usually do this by using telephone poles. I’ll run faster for 3-4 poles and then recover by running slower for one pole.
A day or two a week you should also be doing a weight workout. Now, you’re not trying to bulk up and become a body building. Lifting some light weights (both upper and lower body) will increase the strength in your muscles. You will also be strengthening muscles that you do not use in running – this will help with making you a stronger runner. Also, doing some light upper body lifting will help your arm swing and will help you in the later stages of a long run.
As you can see, building up your stamina is fairly easy to do – but it does take some work. And, it won’t happen overnight. But, it’s a great accomplishment when you add a little more to your longer run. You will feel great when you reach your mileage goal!