When do you choose your own happiness over what is morally right?

Has there ever been a situation where you have chosen your own happiness over what was morally right? Or could you imagine such a situation for yourself? Are there certain times when it is always okay to put yourself first? Are there certain times when it is never okay to put yourself first?

Morally right being defined in whatever way makes sense to you. Your own morals or that of the majority culture etc..

BTW I have nothing in mind here, this thought just kinda popped into my head and I suddenly thought ‘this would be an interesting one for fluther’