I've tried following my breathing for years while running, I have been and continue to be very persistent about it. I still do attempt to "let" my attention be on my breathing. As I have been saying I do not get to a point that I can "just surrender to it". I do not get to a surrendering feeling, I only get to the "forced" feeling. The thoughts in my head do not subside long enough for me to just "let" my attention go to my breath. I have to pretty much force my attention there. I attempt this pretty much every morning while running (and have for years). I fully understand (on an intellectual level) what you are saying. I understand the difference between "letting" my attention go to the breath vs. "forcing" my attention to the breath. I understand that the effort to "force" my attention creates it's own stress (not denying that) but I have neber been able to reach a state that will allow me to just "let" my attention go to the breath.Exercising is a good thing to do first thing in the morning; I bet it keeps you sane (ish).
It is a good opportunity to follow your breathing. That's what I would suggest. As you run just let your attention be on your breathing. And sort of 'surrender' to it. i am sure it will do nothing in the beginning; but all these things require persistence.
From what you say, I think it is important for you to have a "surrendering" feeling instead of a "forceful" feeling.
If you feel the stress at the front of your head, you can know that that is an indication of using "force".
This does sound very similar to the Conscious Connected Breathing that I attempted.Also I second WW's thoughts on breathwork.
At the moment I am doing 20 mins pranayama every day, and I can tell you it is a strong technique. No BS. That's why I do it. Fast, effective, reliable.
It has made all depressions vanish overnight, plus it cleans up the psyche and makes all the spiritual stuff more accessible.
The 20min routine is :
(seated with spine erect)
Bhastrika : 20 breaths then breathe and hold mahabhanda. Then breathe out and relax wait till breath back to normal. Repeat 3 times in total.
Nadhi Shodan : 20 cycles, a good ratio at the beginning is 1:2:2 ( so 4secs in breath, 8secs holding, 8secs outbreath, or - 5sec:10sec:10sec)
You can find instructions for these easily, this is the standard pranayama for yoga and must be 10,000 years old.