“We are uniquely equipped to replay and ruminate on negative feelings over and over and over again,” said Ethan Kross, who runs the Emotion and Self Control Lab at the University of Michigan.¶¶”This process of turning over in your mind over and over and over again, that negative experience, that can become a toxic process,” he said.¶¶Rumination has real health impacts – everything from cardiovascular health to aging – because it’s essentially chronic stress.¶¶”This really is how stress gets under the skin and hurts us,” Kross said. “A stress reaction isn’t bad per se, it’s when we are experiencing stress chronically over and over and over and over again.”¶¶Kross said heartbreak is a uniquely insidious stress response because it invites that replaying of events: If only I’d said this instead of that. I should have seen this sign or that.