How am I going to get through all this work?
I don't know what will happen if I fail?
What happens if we don't meet the sales budget?
I hope that I don't get sick!
If this is a familiar train of thought then you are in trouble!
Pessimism has been found to not only increase stress, but also increases incidence of illness & absenteeism, tiredness, slower recovery from surgery, low self esteem, and causes the under use of abilities.
You simply cannot afford to 'put up' with a bad mood, having a miserable day, or negative colleagues.
Pessimism will drain both your productivity and quality of life.