"Talent is helpful in writing, but guts are absolutely necessary."
It takes guts to sit at a keyboard for days, weeks and months, not knowing if anyone else will ever read your book. There is no one telling you to do it. You have to do it yourself.
Then comes the rejection. Every writer has faced rejection. It takes guts to keep sending out a book and facing more rejection. It takes courage to sit back down and start the next book.
Being a writer is a fabulous profession, but it's not an easy one. :-)