Some stress is normal and even useful. Stress can help if you need to work hard or react quickly. For example, it can help you win a race or finish an important job on time. But if stress happens too often or lasts too long, it can have bad effects. It can be linked to headaches, an upset stomach, back pain, and trouble sleeping. It can weaken your immune system, making it harder to fight off disease. If you already have a health problem, stress may make it worse. It can make you moody, tense, or depressed. Your relationships may suffer, and you may not do well at work or school. What can you do about stress? The good news is that you can learn ways to manage stress. To get stress under control: Find out what is causing stress in your life. Look for ways to reduce the amount of stress in your life. Learn healthy ways to relieve stress or reduce its harmful effects.