MAM #001 – What is mid-life and what is a mid-life crisis?

Our first episode focuses on definition of mid-life, identification of a crisis, and ways to start thinking about it.  What are typical signs and symptoms? Why are these things happening now? How should I be thinking about this?
 
 References:

Triumphs of Experience
 https://www.goodreads.com/book/show/15861579-triumphs-of-experience—the-men-of-the-harvard-grant-study

Needs Theory
 https://en.wikipedia.org/wiki/Need_theory

Self Determination Theory
 https://en.wikipedia.org/wiki/Self-determination_theory

47.2 is the Low Point
 https://www.nber.org/papers/w26641