How can that be?
When something is taxing and difficult we have to focus on it completely, at the expense of all other thought. Once we settle our minds and begin to properly focus (as opposed to quietly panic), true learning begins and real understanding grows. It is this focus which makes the 'pain' enjoyable, and it is the growing which makes us a little bit addicted. If you are simply copying someone elses work, you don't get it. The striving and observing is the creative part, and THAT'S what makes the world go round!