Such as laying on the warm sand of a beach. Listen to the waves as they pound upon the beach and smell the salty sea breeze. Feel the warm sun touching your skin. Try to imagine that you're in a big clear bubble floating above a emerald green valley. Visualize anything that makes you feel relaxed.
Breathing exercises are great for relieving stress.
Breath in a deep breath. Hold it and count to ten. Let out the air and as you do visualize the air as being all the pent up stress. It is very important that one has something useful to do during the day and to stay occupied. An hour to a nervous person seems like forever.