If you are switching jobs:
"I'm leaving the business" is a phrase that requires a lot of courage. When pronounced at the wrong period or in the wrong way, it can have a very negative effect on your profession. You can find a job give with another company where the pay is higher, but you are still uncertain if that work place will undoubtedly be better then the current one. After all, it isn't all about the amount of money. Imagine if you later change your mind? After all, this is simply not a straightforward decision. Needless to say your boss can forgive you and hire you back, but it isn't guaranteed.