then it could be happening when you don't have something to focus your brain's attention.
Exactly. That's part of my problem. The other part is too detailed so I won't get into it. If I have nothing to stress about, I stress worse. You need to be focused on something all the time. It's just how your brain works. That's why I find the concentrated breathing so helpful, as did my son who was ADHD (more the "H" than anything else). Another technique is called the "ooh-sa" (not sure on spelling) technique. Whenever you feel you are going to lose it you go to your "ooh-sa" place. It's a place you can go in your mind where you NEVER feel stressed, be it setting up your unit, in your easy chair in front of the TV, a beach or lakefront place-doesn't matter. You just picture yourself there and focus on that. Sometimes it helps immensely.