Flight attendanta

I've just landed in London Heathrow. I was sat in the very front row and as we were waiting for the doors to open I said to one of the attendants "you two should start a business teaching the other airline staff how to be friendly"

She looked at me - surprised - and said "Thanks. I only ever fly BA. Don't the other airline staff enjoy their jobs?"

Simple equation; enjoy your job -> smile -> customers happy -> repeat business.