Sometimes writers forget to think positive when it comes to their work. It is hard to do when you don't have a support system while sitting alone working on a story. We all suffer at one point or another. Until we receive a steady paid from our writing, you cannot avoid the negative thoughts. Can we finish this manuscript? Will any agent pick it up? How many rejection letters is this one? We base our worth on what others think of us. A published writer will garner more praise and awe than an unpublished writer.
But even if you make a living off of writing, the constant demand to keep up your status of a published writer can bring negative emotions. At times a 'has been' is worse than 'hasn't been.' The notion of 'you can do it' but 'can you keep it up' will wear you down. Plus the discipline needed to keep all your finances in order because you may need to live off of your savings until the next pay check arrives.
While most people suggest be positive, I suggest be more positive than negative. When I am down, I'm very negative towards myself. But once I crack the wall, I gain positive thoughts but still keep the negative ones. They co-exist inside my mind and heart. I would not be the person I am today without them. As long as the good out weight the bad, I will never lose sight of my dream. If you accept the bad, the good will always follows and that is the key to success.