Yeah, take whatever seems reasonable (advice from personal experience. do no take Phenergan unless you are sure it won't turn you into a rolling drunk)
I've got a counting program I use when I have to get into unpleasant machines or people want to stab me. Start counting backwards from 27, three second breaths in, three second breathes out for each number. Then from 26, then 25 etc. If you can hold it together, the program thing takes about 45 minutes. If you forget where you are up to, you have to start again.
When I assume the required position, I tell people not to talk to me. Some well meaning do-gooder usually fucks it up. But I start with good intentions. It has worked for me. So have drugs. Best of luck. Mxx