Mindfulness gives you time. Time gives you choices. Choices, skillfully made, lead to freedom. You don't have to be swept away by your feeling. You can respond with wisdom and kindness rather than habit and reactivity.
Bhante Henepola Gunaratana (2010). “Beyond Mindfulness in Plain English: An Introductory Guide to Deeper States of Meditation”, p.43, ReadHowYouWant.com