Here are several tips to follow to think more positively at work:
Appreciate the small successes. …
Take time to cultivate positive thoughts. …
Make every situation a lesson learned. …
Surround yourself with positive people. …
Use positive language. …
Express gratitude. …
Write down three positive aspects of each situation.
Source: https://positiveworklife.com/ways-to-keep-a-positive-attitude-at-work/