Getting something you want can be hard work. For example, if you want good grades you of course have to work for it. It may be easy to say you want good grades but the challenge is to work hard for them. Good things don't just come out of nowhere and land on your lap, you have to put in some effort because otherwise your not gonna get anything you don't work for. Therefore, good things come from hard work another way of saying that you have to work on what you want to get it.