Most of my Early retire friends here in town (who like everyone who works on Wall Street generally hate it and/or know they will get pushed out one day) have "The Number" in their heads for many years. "The Number" is the amount that they assume they will put into muni bonds at prevailing interest rates and cover all their annual lifestyle expenses. Leaving aside the fact for now that it is a dumb strategy (doesn't keep up for inflation, don';t need muni bonds when your taxes are so low,), the principle of having an assets target is sound.
I had my own "nuimber' in mind for many years, used a too-high SWR (5%) and ended up raising my number by 50% before I stopped (lifestyle creep, and arguably still not quite high enough) but the basic method worked. Never had a pension and it never entered into my calculations.
Realizing that I couldn't get to my number on a safe route of saving at employment incomes (and never had a safe job anyway), I knew I had to take on more risk and do something audacious to ever make it to my number. So I started two companies. Somewhere in the middle of the dotcom blur we sold the first one to a public company and its share price zoomed up, so knowing my number meant I sold steadily into that insanity. I am still one of the few people I know who walked away with the lion's share of my dotcom gains, and I attribute it solely to having known what i wanted and needed to get, and then just taking action when I got there.
The value of the number for me was knowing I wasn't going to reach it on the path I was on (regular employment even in the escalated risk-reward role I moved myself to -- sales and sales management), which provided the clear spur for me to go out into the cold and be an entrepreneur. (which also involved investing meaningful sums in the startup phases of my companies -- 100k for the first one, 500k for the second -- something that would have been impossible to pull the trigger on if I hadn't known where I was going to and why.)
The Millionaire Next Door research bears out that many people who accumulate 1m+ take a similar self-employment path.
Bob