Let's say that you worked on your relationship with running, and you've managed to conquer a few 5ks here and there. Now you're a little confident about yourself, ready to do distances that are longer. You think that the marathon may be too much for you right now, but the next step is running a half marathon. What should you do?
Simple... in a way...
Keep on developing that relationship with running, and do the same thing you did for the 5k. Instead, you'll be going out more, and your runs will take more time. It requires a deeper relationship. The bigger the goals you have, the more you need to be committed to it. Just as the bar gets higher, you need to work harder. It's not easy to just do the same thing and expect different results. If you want better results, you improve your quality as well as quantity of practice. When running a 5k, the amount of time prepared to train for that is miniscule compared to that of a half-marathon simply because of the difference in distance. A 3.1 mile race is 10 miles shorter than a 13.1 mile race. It's only obvious that you would train more for the longer race.
The ratio between a 5k and a half marathon is almost 1:4. That's a big difference. It means that you'll have to train a little more, in order to achieve results. It doesn't matter if you're a veteran or novice, the training is going to require the individual to run longer. The level the individual is may be different, but the amount of practice will definitely be increased. The 10 mile difference will push the individual to go harder and longer. Some people may have a harder time adjusting to the amount of mileage they should be doing per week in order to achieve their goal. A simple thing for me is to do two runs in a day. If you do one run, you might be able to do X amount of miles, but if you do twice, you'll run Y miles in the morning, which would amount to a little more than half of X, and at night, you'll run another Y miles, helping you go even further.
Sometimes, going for goals means that you have to divide your workload into two in order to get half done early, and the other half done later. Divide and conquer is a tactic that is used not just for group work, but running, and achieving goals. Today, I hung out with my friends... but tomorrow, I'll be running twice, making sure to get my mileage, and keep my body rested.
More miles run = able to run longer
Such a simple formula.