The important thing is to declare your intention before you run. "I like to be in communion with my God as I run."
Today I ran on the treadmill in a gym. It was nice and warm outdoors but my son requested to run in the gym so he could do some strength training after a run. Anyway, I find myself running in the gym more frequently this summer, which is really not a bad idea at all.
However, praying while running in the gym is not too ideal. I went through the basic meditative preparation as suggested by Robert Joslin in his book "Running the Spiritual Path." As I started picking the pace on the treadmill, I focused on my breathing. But the blaring music all around seemed to be muffling my breath. I could feel my exhale as the intensity of my run started to pick up, but my other senses were picking up too many stimuli. My eyes kept on panning the 10 TV screens sprawled across in front of me. My nose could smell my own sweat. My sweat kept trickling down my face. All these were nothing new to me, except that I realized it was too hard to take the first step of a meditative running in a gym. However, I persisted and I tried to be aware of my legs as it touched the ground. Actually it was no ground. As you know, I'm running on the treadmill. But I did visualize myself running on a bridge over the waters. This is good because this is something I will actually do when I run the San Francisco Marathon is a few days. Then I let my thoughts wander but reminding myself of my main intention for this run. "I desire to be in communion with God." Every time I did this, I felt that all the external distractions became part of my praying. It wasn't a very meditative type of praying but I sincerely felt in my heart that I was aware of God's presence.
At the beginning of your run, remember to declare your intention to pray. Ask God to give you the grace to meet Him as you run. I am sure He awaits and is ready for you and is even running towards you.