Rate of stamina loss

[d3ath4u]

This question is geared at all you beta testers out there. I have been aware of stamina being in PS since the beginning, but I never really thought of it as anything else but Mana points in a FPS. I just figured that you would lose stamina when you use implants, and maybe a little if you try running across long distances. I was bored one day and decided to play the half life mod (or maybe it isnt a mod) and i noticed that when i ran around, I started losing stamina from the get go. I couldnt run 200 meters without taking a breather. I have been looking at all the screenshots i can , and as far as i can tell, you lose none or very little stamina when doing anything else but activating implants. So beta testers, is that how the stamina will work? or is running around/shooting really a factor for stamina lose?