Scent works fastest for me. I prefer a scent I like, but the ptsd psycho-education people taught us that unpleasant strong smells are even more effective than nice smells - they were talking about smelling salts, which, helpfully, had just been banned in the UK but hey.
So I use Olbas Oil instead, not as unpleasant, but available to buy.
They told us that our sense of smell gets through to our brain quicker than anything - fraid I forget the science behind it.
My next fav thing is slow deep breathing right down into the belly. And letting my shoulders drop with each exhale.
Icepack on the back of my neck.
If I'm not too far down and not strongly wanting/needing to isolate, talking about "normal" things with a close friend - it helps to hear about their day.
Best will always be having a dog.