Hi @AnxiousMe
The way I see it, you're disconnected from your body when you're flighty. Mindfullness grounds you which means life seems more clear and conscious. 'Thinking' all the time trying to fix how you feel, or on your laptop looking for clues, means physical life's passing you by.
Getting your hands in the dirt for instance brings your brain/body back into physical reality and out of your head. Focusing on housework (auto pilot 🙂 ) will also clear your mind. It's a huge relief, if not only for a few moments, but at least you'll understand the difference and that it works. I used to have those disconnected feelings all the time, but trained myself to catch it when it happened because it happens without even thinking.
Giving up smoking isn't just about brain chem's, it's about self medicating to avoid certain feelings. If those feelings emerge without cig's to rely on, (unconsciously) our brain tries other ways of avoidance. This leads to dissociating; that's the weird feeling of not being present.
You could be triggered by anything that puts pressure on you. Eg; not eating in the mornings, (hyperglycemia) imagining pictures in your mind different to what's happening at that time, (the brain can't do multiple things when it's damaged) unpleasant movies/books/music or anything that reminds you of unpleasantness. Healing your brain takes time, so resting it by doing mindless physical tasks will benefit you greatly in the long term.
You're a combination physical/emotional/mental/spiritual being, so your brain has a lot to deal with. Simplifying your life makes things so much easier. You need to retrain your brain so it works effectively again.
Mindfullness is anything that gets you back to physical reality. It's really important. There's loads of info on it to be found online, in books or on this site.
Hope this helps 