This was going to be a long post, filled with context and backstories, but it didn't make sense that it should be so, given the key message it is meant to communicate. So here it is, in a very abbreviated form.
I've learned a lesson through my personal walks of life and from the wisdom/insights of those who have mentored me, that The Formula for Happiness is not complicated:
Happiness = Outcome - Expectations
That's it. Simple. Easy.
All the personal development stuff out there is targeted towards either increasing Outcomes, decreasing Expectations, or building the awareness to appreciate what is present.