Have you ever hired a manager who remained relentlessly cheery despite real, worrying challenges in the business? Did this person expect their team to maintain a constant smile?

Have you yourself ever felt the need to project enthusiasm and optimism to a mentor or investor despite feeling exhausted and afraid? Were you ever an employee who pasted on a smile despite serious troubles in your home life (or the world at large)?

Ever decided a relationship wouldn't work out because the other person couldn't bear to handle anything but perpetual (if possibly fake) good vibes?

All of these are common scenarios of what psychologists term "toxic positivity," and scientists are beginning to understand how the pressure to be relentlessly optimistic affects us. Given that today is National Smile Day, it's a good time to remind ourselves of what they've discovered about the negative effects of the pressure to always keep smiling.

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"It's a problem when people are forced to seem or be positive in situations where it's not natural or when there's a problem that legitimately needs to be addressed that can't be addressed if you don't deal with the fact that there is distress or need," University of Michigan Ann Arbor psychologist Stephanie Preston has explained.

Read the complete article in Inc.