In this line of work it‘s hard to remain optimistic. You deal with mistakes, bugs, ignorance. You repair more than you create. You often work for those who cannot comprehend what you do. Your most carefully laid plans unravel owing to the incredible complexity of distributed systems. You begin to expect the worst out of computers and people.

 
From  the not-for-profit Positive-Posters.com and neatorama.com

Remember the important things you are doing. The successful deployments. The proposals fulfilled. The problems fixed. The satisfaction that comes from your efforts making a real difference.

As Winston Churchill said, “I am an optimist - it does not seem to be much use being anything else.”

- Ned Pyle