A grey outlook reminds me of Eeyore = "Woe is me..."; think the world is dark and gloomy and it will become dark and gloomy. I know it's trite but it's also tried and true - look at the positive side of things, add some humor, don't be afraid to laugh at yourself.
I have two author friends fighting for their lives against cancer and they both are maintaining a positive outlook and their humor. They can't change the fact that they have cancer but they can change their outlook on it. Both are doing well and continue to laugh in the face of terrible adversity.
Can we do any less?