Consciously relaxing your body and mind is really helpful, not just in the early days of quitting, but as a way of dealing with stress in your life. Simply close your eyes and slowly take several deep breaths. Begin breathing from your diaphragm and count to five as you slowly inhale through your nose. It helps to place your hand on your abdomen. You may want to imagine your breath filling your body with energy, and then pulling all tension out with it as you slowly exhale as deeply as you can through your mouth.
Most smokers use cigarettes as an emotional coping tool, in lieu of tools that do relieve stress. Are you feeling stressed right now? The need for relaxation will often disguise itself as the urge for a cigarette. Here's something you can do right now: if you're standing, find a chair and sit in it calmly. Close your eyes. Take in a deep, slow breath. As you gently release the breath, silently count, '10'. Repeat the process for the number, '9', and so on down to '1'. Let your thoughts move as they will; you don't have to empty your mind to relax. Just breathe in and out, and focus on the count. This won't take but a few minutes and you'll be surprised, after you've tried this for a while, how effective a tool it is for calming down.