Here's the secret to being able to run long distances: It starts with a dream. It starts with you believing something is possible, that it is possible for YOU to do it... simply put, if you have dreams, go for it. There's nothing stopping you from achieving that goal. It's a lot more simpler than we realize, but at the same time, it's hard to go by. To some people, it's the dream that they cannot conceive. To others, it's the commitment to that dream they cannot follow.
When I train people, I always start at the beginning and ask them about their goals and what they want to achieve in this time they're training. First, we set up the end goal. I usually hit high because I like challenges, and it's through the challenges that people grow. When I mention running a half marathon to a friend of mine who asked me for help, he looked at me surprised and said that it was impossible. In reply, I told him that of course it was impossible for him to do it now, but not impossible for him to achieve that goal in half a year. He looked at me and was amazed at my confidence. Not in myself and my training, but in him and his potential. We talked about different things he could do to get there and little by little, he became excited about it. I enjoy coaching people and helping them get into their dreams because it truly is something that is wonderful to see. You see the excitement build as they begin to understand the possibility that they could run that distance if they worked towards it. In their heads, gears clicked and a light went on. The potential was already within them, but it just hasn't come out.
Now the continuation of that path is different. Each individual has the potential, but not every individual has the will to make it to their goal. They are not able to because they lose sight of what their goal is. Keep that goal in sight and working towards it takes a lot of discipline and not everyone has that. Which is usually why coaches are there. Coaches encourage athletes, giving them the push that they need when they feel weak. It doesn't matter what sport there is, a coach gives the team inspiration. It doesn't matter where we are in life, we have life coaches everywhere, our family, our friends... and they encourage us as we go towards our goal. When I'm not with my friend, I have a harder time training him because he doesn't have that constant interaction with me... with his coach, but we do what we can with the limited interaction. It's good to have someone there with you to push you forward, because we can't all be strong at times. I have trouble myself with going forward. There are days where I feel tired and don't want to go all the way, but I look back at where I was and look forward to where I need to be, and if that's enough... I push forward and continue on that path.
It's up to you whether or not you'll be able to achieve your goal. The balls on your court.