If it’s not fun, you’re doing something wrong.
The authors talk very little about actually having fun and more about finding the clicking point where you realize that you enjoy lifting and what it can do for your body. If you do not enjoy what you are doing, then you will not be in it for the long haul which is what is necessary to get the most out of any program and to maintain a healthy body.
I have to agree with the sentiment though. If you are not enjoying yourself, you need to try something else until you find something that you do enjoy. Weight lifting, running, bicycling, swimming, basketball, turning cartwheels in your front yard: they are all just a means to an end. Keep moving along until you find something that you like. Also, don’t forget to go back to things you tried before and try them again. You may find that you enjoy them more when you are coming at them from a slightly better fitness base gotten from some other activity.