Does pessimistic thinking increase the probability of bad results?

I survived a health issue at 16 years old and was invited to a free survivors support group for those with similar issues, but I realized, I am one of the few in the group that does not appear to be at risk of new incoming afflictions based on the previous trauma and I think if I talk like I never recovered, I might increase the risk I will get sick a gain.

Does pessimistic thinking increase the probability of bad results?
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