ok, if it is from stress, and you do yoga, then the following should be easy:
lie down on your back
close your eyes
fold your hands on your belly
breathe deeply and naturally against the weight of your hands
don't "try to clear your mind" - that's lunacy, like "don't think of a white horse". Just feel your breathing as thoroughly as you can
eventually your thoughts will fade
you will feel your own heart
project the awareness of your pulse down into your extremities
bring that awareness slowly back to your center
you should be left very very calm.
I'll try that. I don't meditate or anything like that when I do yoga. I just do it to maintain my flexibility.