I agree with a lot of what people have said here about a job being a job. However, my personal experience on this subject is — start with defining what happiness means for you!

This is a LOT harder than you think and in trying to answer the question you will hopefully (as I did) get in touch with yourself, your emotions, your identity, etc.

As you continually evaluate these things in trying to understand what happiness is for _you_, you will automatically have an answer to your question.