The idea of "lifequakes" or "lightning-strike moments" is taken from the book "Life is in the Transitions", by Bruce Feiler. To summarize it, there are moments in our lives that cause upheaval and result in our taking a different path than we were originally taking. We can't see these moments clearly when we're experiencing them, but looking back on our lives, we can identify at least some of the moments that caused changes in our life trajectory.

Retirement is one of those moments, for sure, and whether it comes as an expected change or is thrust upon us by some outside force (like maybe a pandemic...) there are changes. What we  with the moment - and the changes - is up to us. Why not make the most of it?