After something stressful has occurred it would be nice if we could leave it behind and move on with our lives. Sometimes we can. For example, you might narrowly miss getting sideswiped by another car, feel stressed in the moment, and then shake it off and move on with your day.

But often after we’ve encountered a stressful event, say, an argument with a spouse or an important presentation at work, we continue to ruminate (have repetitive, often negative, thoughts). These thoughts are not about active problem-solving; they are repeatedly chewing on and worrying over past events.

Why is it that sometimes we can let go of the things that stress us out and at other times, even after the event has passed and we know can’t change it or our response, we continue to be stuck thinking about it?

It is important to understand what makes us more likely to dwell on the past, considering the numerous negative consequences.

Personality plays a role. Some people are more prone to rumination than others. Nearly everyone dwells in the past at some point, but some people do it more often and are more likely to get stuck in their thoughts.

But are there types of stressful events that make us more likely to ruminate? Recent research indicates that stressful events that have some sort of social component are more likely to stick with us (Emotion, August 2012). So, for example, a public presentation is more likely to leave us dwelling in the past than a private stressful experience.

It makes sense, of course. If we’ve had to perform in some way or another, we are then more likely to worry about others’ negative judgment. Not only are we more likely to worry, we’re also more likely to feel shame.

It can become a vicious cycle. We have a stressful experience in public, we worry that how we acted won’t be accepted by others, we feel ashamed of our actions (justified or not) and then we worry some more. The more shame we feel, the more likely we are to worry.

Shame also appears to be linked to rumination and negative thoughts. Shame occurs when we fail to achieve our goals. Unmet goals tend to leave us focused on the goal. Feelings of shame — for example, shame at not achieving what others have, shame at not being good enough — can cause us to overthink things and become stuck in negative thoughts of past failures.

Rumination and persistent negative thinking are linked to social anxiety, symptoms of depression, elevated blood pressure and increased amounts of cortisol (a hormone associated with stress) in our blood. This type of worry can last three to five days after a stressful event has passed.