Your thoughts have a big impact on what happens in your life. If you go into a situation with a positive attitude and think you will succeed, that can help you succeed. But if you go into the same situation with a negative attitude and think you're going to fail, that can lead to failure.
Let's say you're taking a test. If you go into it thinking, 'I am totally going to ace this!' you might do really well. However, if you go into it thinking, 'I'm going to fail anyway, so what's the point?' you're likely to get a low grade.
Remember, your thoughts create your reality. So, try to keep a positive attitude, think positive thoughts, and see how that affects your life.