[grownseed]

I don't think having few expectations necessarily means numbing down your life or your emotions. I think you simply find that there are many things that needlessly take space in your life or might make you act poorly towards other people. As a personal choice (which of course doesn't have to apply to everybody), I've lowered my expectations to something that basically boils down to "being a better person". It's the biggest drive I have and it requires very little with the exception of learning, understanding and empathizing.

"[...] plow through and find some happiness or a silver lining"

What you're suggesting here is that happiness has to come in bursts (for lack of a better word). While I think that can be true, I believe the kind of happiness the OP is referring to is more deep-seated. By no means does it exclude other emotional states, but it reduces anger to a minimum. Although "Disappointment, heartache, sadness, and gloom" may be constructive, I honestly don't think anger is.