If I fail, I try again, and again, and again. If YOU fail, are you going to try again? The human spirit can handle much worse than we realize. It matters HOW you are going to FINISH. Are you going to finish strong?
The best time to negotiate your salary for a new job is the moment AFTER they say they want you, and not before. Then it becomes a game of chicken for each side to name an amount first, but it is to your advantage to get them to give a number before you do.