Why do we run ? According to my experience, we run to flee (from an aggressor or from our anxiety), to hunt (a bus when we are late or a deer when we are hungry), to play (with our friends on Saturday morning).
Running is a global experience. With the feelings on my skin, I know the quality of the air; with the feelings on my feet, I know what is right under my feet where I stand. With my eyes I know what is just in front of me. With my nose, I know what I can't see, what is behind the next bush. With my ears, I know how things move in any direction, especially what is behind me and on my sides. The touch for the present and where I stand; the hearing for the past and what is behind me and on my sides; the view for the short-term future and what is right in front of us; the smell/ taste for the long-term future and what is far ahead.
Being mindful of my sensory system helped me to get rid of pressure of performance, and improved my technique and posture. Indeed I think we have this finely atune and precise global sensory system for one and only one thing: to adapt, to adjust to our environment. It's not our will or desires that shape our behavior, but the interaction between our capacities and the environment. It's not a pair of shoes with flying wings that dictates if I can run fast everywhere, but how my body can react to my environment with its capacities. If you start thinking about how it hurts to run on sharp rocks, and start thinking about the reason behind this kind of pain (I mean ache not suffering), you begin to realize that your sensory system is not just bothering you and preventing you to achieve your PR, but telling you how to adjust to your environment with the capacities you have. The interaction between the environment and our capacities show us how we can adapt to the features of our environment with efficiency and safety. (Consequence: don't mess with things that alter your sensory system and your brain chemistry, or seclude your sensory system from its environment.)