ACOC, that's a pretty good definition of mindfulness. The particular aspect you mentioned above, is what I have found very helpful. I have experienced the lessening in symptoms when you commit to letting the negative emotions or thoughts exist without becoming reactive. It's like you move through the anxiety and come out on the other side of it. As much as we would rather avoid feeling anxious, fighting it doesn't help. Even if we're only fighting it in our minds.
Originally Posted by acoc100
Acceptance of emotions particularly distressing ones (anxiety, panic ..etc) and being willing to allow them to be there is another aspect of the mindfulness incorporated in ACT.
Anxiety is a lot like getting caught in an undercurrent, I think. If you panic and begin to fight for your life you will drown. But if you go with the current, eventually you will be able to swim free of it. It takes a lot of nerve to not fight because it feels like if you do you will drown. But in the end not fighting is what saves you. That's what mindfulness teaches you.