Learning to listen to your body and not paying too much attention to what your head is telling you is very important.

For both purposes I use: music and... experience. The first helps you take your mind off your breathing, the second one gives you a sense of perspective about how much of what you are experiencing is real and how much is just your heads playing tricks on you.

I recommend that you find a way to enjoy your run, for me it is a time of day when I fight off stress and have some "me" time. I leave home, turn the music on and see miles go by. Sometimes I think about work, sometimes I focus on the music and, yes, sometimes I think about how tired I am, but most of the times I am just enjoying the feeling of being out there running (because it is summer or winter or cold or night or even because it is raining). How to discover what you enjoy about running? I would suggest not overdoing it, walk if you cannot run (and maybe go back the next day), if you are too tired today, keep at it a while longer, and if you have to, stop, but come back the next day.

Once your run is not only about effort but also about other things, then you will stil need to keep an eye on your body so you do not overdo it, but experience will tell you when you are really at your limit and when you ara just having a bad day (sometimes you can "outrun" these). Do not worry too much about your limits, they are there, and are difficult to overcome, but if you keep at it (mainly because running is something you like to do), then they will keep on rising.

Keep up the good work!

I have always had a very strong internal motivation to run - for me, it feels good to exert myself and drip sweat, I like starting the day doing something good for myself, and it's a combination of precious "me time", stress relief, an opportunity to challenge myself and escape from the rest of the world for a little while. I'm always looking for excuses to run. Never excuses not to run. Seriously. But that said, a little external distraction can go a long way. I almost always train with an iPod because the music distracts me from how hard I'm working and makes the time go faster. When I do a training run without music - for example if it's raining and I don't want to soak the iPod - the run really does seem longer. So I would also recommend music or whatever you like to listen to (podcasts, audiobooks, etc.) to accompany your runs. Also...you mentioned running on the treadmill. Even for those of us who love to run, the treadmill can be a real test of one's patience. I would recommend running outdoors if at all possible. Personally, I can do up to about 4 miles on a treadmill if I have enough distractions (music, TV, etc.) and even then I often spend a lot of time playing with the speed controls to keep my mind busy. About the most I can withstand on a treadmill is 7 miles (an hour) - and only if the distractions are top of the line. The same distance outdoors would fly by.