Catharsis decreases stress
If agitation evolved to get us moving, and if moving stops agitation from building up, such as with optic flow, then engaging in a challenging task might decrease stress. The effort underlying the process might signal the body that the goal of the agitation build-up has been reached, and that there’s no need for more. Essentially, catharsis blunts the stress response. What’s more emotional writing or journaling might be catharsis mechanisms.