Author Ruth Galm received upwards of 60 rejections from agents for her first novel, Into the Valley. But she kept working, and after years of revising the book, it was plucked from the slush pile at Soho Press. Into the Valley comes out in August 2015, and it's already received a starred review from PW
Galm discusses the writing process, and persevering through rejection.

When I think of perseverance, how perhaps I persevered in the face of mounting rejection for my novel manuscript for Into the Valley, published by Soho Press this month, I feel no greater claim on this state than any writer I know who carries on doggedly every day. Publishing my debut novel took many years and pushed me from my 30s to my 40s. I can share a few particulars of the journey with the caveat that for some my path might seem like a cakewalk; that I do not presume to know any more how to persevere than the next. 

But I know stories from the trenches helped me in my most doubtful times, and so I will offer what I can with the disclaimers above, and the hope that it finds you recognizing the quiet, accretive strength of your own resoluteness.