Sit with your eyes closed and imagine your favorite, peaceful scene. I like to imagine the beach, with gently rolling waves or a waterfall in a chain of rugged mountains. Then, working your way up from the tips of your toes to the pores of the hair on your head, concentrate on relaxing every single muscle, big or small, in your entire body. Feel the stress melt away throughout your entire body. Breathe slowly, deeply, through your nose and choose a simple word such as "ah" or "peace" to repeat aloud every time you exhale.
10 minutes or so of this will do an awesome job of relaxing you, but if all you've got is a minute, squeze it into that minute. One minute of relaxation is better than none. I feel better just thinking about it. Let me know how it works for you. I'm always available at firstname.lastname@example.org Enjoy your day!