'Be yourself...after all, who else can you be?', they claim with a casual, almost cavalier presumption. 
As if the notion of self realisation is a fait accompli. 
Rubbish.
I can be anything but myself with astonishing alacrity. 
Never underestimate the pain and suffering that come from trying to be who you really are, in the face of enormous adversity; from other people, as well as from yourself.  
Such underestimation has killed many along the way. 
So don't sell short the perils and pitfalls of 'being you'.  It's a tough road- & knowing this can be of great comfort in the long run.
And this is, after all, about the 'long run'.
The Long Run of the soul.