When I am extremely stressed, I get very shaky and there is no hiding it, can'y hold a cup of coffe without spilling it. The one thing I do no matter what, is I go to a quite place and say to myself breathe, deeply in the nose and slowly out the mouth, I sometimes can only do it a minute but sometimes ten. Every little bit helps. I learned this in the mid 1970s, before yoga, concentrating on breathing became popular. I still practice this every day.