I'm pretty sure it's some sort of guide to good psychological health for people in the business of theatre, like how not to get depressed from rejection and things like that. Or, it might have just been for playwrights, or just for actors. But I'm pretty sure it was just theatre in general. I think it had a fairly long title, and the cover was gray, if that helps any.
Of course I could just go back and see if the book is still there, but it's raining and I'm low on gas. :)