GAPrunning

"and when i run, i feel god's pleasure"
—eric liddell

Physical

Physical form is important to how well you run. If you're expending energy on the wrong things, your run will suffer, and you'll tire more easily. Don't try to implement all of these at once. You'll be paying too much attention and won't be able to actually run well. Start small, get one or two to the point where you no longer have to expend any mental energy to sustain the habit, and then move to the next. All of these things synergize well; if you're breathing steadily, you'll be more relaxed, etc.

Relax!!
It is very easy to tense up, especially in a race, and the energy expended can add up in a long run. There are two places that will indicate if you are relaxed enough: your face and your hands. If you watch slow-motion video of sprinters running you can see their cheeks and mouths flopping all over the place, because the muscles are completely relaxed. Distance running is a little different, and when you're straining at the end of the race it's not a big deal, but during your run you should relax your face. No grimacing! As for your hands, they should be loose. They shouldn't be out of control, but you shouldn't be making a fist. I remember the first 2-mile that I ran in high school. By the end of the race, my arms were burning and felt like they were going to fall off, because I had my hands clenched for the entire race. What I do now is touch my thumb and middle finger together. This keeps my hands from being all over the place, but doesn't take any strain or effort.
Run Straight
This seems obvious, but it's amazing how many people you see running whose arms and legs are flailing all over the place. Any energy that you're expending not in the direction that you're running is wasted, so try to be conscious (initially) of where your arms are.
Look Forward
It's important to keep your eyes up and your head level. Don't look at the ground in front of you when you run. This enables you to see where you're running, who you're chasing in a race, and keeps you from running "into the ground". All of these physical aspects contribute mentally, but this one surprisingly has even more impact than the others.
Breathe Easily
It is understandable if your breathing is ragged at the end of the race, but you should make the effort to keep your breathing steady, and on even counts. Ultimately you have to make sure that you're getting enough air, but a breathing pattern helps steady your mind. A simple way to do this is breathe with your stride, so that you're breathing in and out when the same foot hits - I use my left foot, as it's your inside leg on a track (this can also help when you're running through a cramp). e.g. In 2 Out 2, or In 2 Out 2 3 4, or In 2 3 4 Out 2 3 4 (better, but tough until you're in good shape). You should breathe as much air in through your nose as possible, and breathe out through your mouth. When running in warm weather it's not as big a deal as in cold weather, but it's still good to do.
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