True a million times over. In most contexts, trying to repress your emotions (emotion or expressive suppression) is the most damaging response you can have. It destroys executive performance and cognitive function and chronic suppression is associated with a host of disturbances (especially depression) and is even correlated with suicidal ideation.

http://psycnet.apa.org/journals/emo/15/1/78/

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2839199/

http://spl.stanford.edu/pdfs/2003/Gross%20&%20John.pdf

http://onlinelibrary.wiley.com/doi/10.1111/sltb.12076/abstra...