What is fog?  You know it as dense clouds that settle so low that they obscure the view.  Is this not why you claim to be “in a fog” at times when the brain is muddled?  Many things can cause this mental fog:  grief, tiredness, over-exertion.  Whatever the cause, just as with physical clouds, know that it is a temporary state.  Most important, know that that which the clouds obscure —the light of pure Awareness, has not gone away, cannot go away.  Ride out the fogginess.  Be good to yourself.  Get the oxygen moving through your physical body.  Movement, like wind, clears away the clouds.  Soon clarity will return, and with it, peace.  You are so very loved.