The human body is no different. Sure you can work 80 hours a week without a break and convince yourself that you are getting used to it. At the end of the day your effectiveness and efficiency has probably dwindled away to a standard you aren't happy with. Take a break. You'll feel so much better for it and more often than not through your own sub- consciousness you will have solved many of those things that were problems before your break.
Prejudices severely limit our ability to respond to change.
Prejudice asfixiates creativity and stifles innovation. They hated each other simply because of their family name. There was no way they could achieve anything together while they were feuding so brutally. A prejudice could be as simple as not buying Cuban sugar or Japanese motor vehicles because of some silly embargo or maybe your family had reason to dislike them in the past. Seek out new friends and acquaintances of different cultures, ages, and values and learn from them.