Sometimes it feels really good when you set yourself a target and you can reach it or beat it. It is particularly good when the target is not easy. This is called challenging yourself. When you work hard to achieve your challenge, your heart rate and breathing will increase. When a challenge seems really hard, you can feel like you might not be able to do it. It helps when you believe in yourself and show courage to give it your best try, even if the challenge is really hard.