It's the idea that in order to lead healthy, happy emotional lives we need consistent habits and exercises that support our mental health and wellbeing.
Instead of succumbing to a knee-jerk negative reaction when you become upset by someone else's actions, slow down and consider if there are other ways of explaining the situation.
Even if you don't change your opinion regarding what happened, the additional time spent thinking about it may calm you down enough to opt for a more constructive response.
After a particularly stressful experience, go for a gentle walk. Keep yourself moving at every opportunity to calm you down.