The "fight-or-flight" response is your body's built-in response to stress. When faced with a challenging or threatening situation, your body produces adrenaline, which increases your heart and breathing rate and improves your response time. Many things, called stressors, can trigger this response. A stressor can be a physical danger, a high-pressure activity, or even performing in public. In most cases, your body relaxes and the adrenalin fades once the situation is resolved. When your "fight-or-flight" response continues, though, or is triggered by a concern or preoccupation with something that might happen, it becomes anxiety, a state of worry that has negative effects on your health. How you choose to manage stress cope with anxiety can have long-term effects on your well-being, so it's important to understand the difference and how to deal with them.