Take a deep full breath into your lungs. Let it back out fast. Do this 3 times. It is supposed to oxygenate your brain and lessen anxiety.
I agree with FT. It's the psychology of the cigarette and why people feel it releases stress. Change your posture. Take several deep breaths. Counting to ten, the old stand by to compose yourself when angry.
Tense and relax all your muscle groups. Start with your feet and work up to the top of your head, don't tense like you could hurt yourself, just enough so that you break the cycle of tension producing a mindset and the mindset producing tension.. deep breaths as mentioned are good.
I'll second this as the fastest way to relaxation. You may be useless the rest of the day, but very relaxed.
lol. Reminds me of a Far Side cartoon. The cartoon pictured a vetinarian examining a horse, he opens up the manual and all the answers were the same regardless of the ailment. "Shoot the Horse". Whenever a poster seeks advice on anything, invariably someone will suggest one of the three you posted as the cure for whatever ails ya. It would be funny as hell to open up the psychiatric manual and find all the pages were blank except for the first one: "Take a dump, rub one out, and then yea smoke a joint." That'll be fifty dollars.