Some basic meditating might easily replace stress and tenseness with peace of mind and relaxation.
An over simplified effort might be:
Find a quiet place by yourself.
Get in a relaxed position.
Rest your eyes downward, almost closed, not tight.
Breathe slowly and naturally.
Do not think about anything else except what you are doing.
Do this for 15-20 minutes.
When lying wide awake in bed, or taking a calming break, try fixing your eyes and thoughts on an insignificant mark on the wall, a small glittery area, or perhaps a shadow. Keep staring at this and think of nothing else. As your eyes wander off bring them back to the object. With practice this will often send you off to a dreamy, peaceful state. (This is not advised while on the job or in the classroom.)
"Meditation has been defined as the cessation of active eternal thought" - Helena Blavatsky (1831-1891)