> We first asked them to rate their well-being — their happiness, if you will — along with their optimism, and then tracked which soldiers later received awards based on their job performance.

I'm curious to dig into the paper more because at first glance, I feel somewhat confused they seem to say happiness and well-being and optimism are all essentially the same thing. Again, maybe their paper doesn't say that and it's just their attempt to summarize it, and maybe some people see those three as different words for the same concept, yet I imagine many wouldn't.