Is there more to your story? Were you getting paid time and a half overtime for all of those hours above 40 hours a week? Did your boss limit you to 40 hours because he had been told by his bosses to limit time and a half overtime?
I agreed because working 56 hours no overtime was a better deal than having the hassle of working two jobs. It is alao better taxwise, because they really punish you when you work two jobs.