When I first started lurking on this site, I recall a spirited discussion on the term, "Critical Mass" and how it relates to the size of one's assets. There were many opinions and well reasoned points. I don't remember most, but I do remember figuring that my own definition would be $750k NW plus a paid off property. Which coincidentally was also my number for a spare, if not quite spartan, ER.
My current invested assets have reached this number today! A couple years late, but likely not too late. I plan on toiling full time for the foreseeable future for a few reasons: DW is currently not toiling and her meds are only affordable with health insurance; I'd like something more than a spare ER, I like travel and comfort; I've managed to empty my BS bucket by a few scoops and am not too near my limit; I've been deferring home maintenance the past few years and am a better engineer than roofer, plumber, mason, etc.; my car is 15 years old and in decent shape, but probably won't reach 30; my water heater and furnace are 20 years old and getting sketchy.
Still, Critical Mass is a huge milestone! Next steps are to slowly adjust my AA to 90/10 equities to cash; take some time off this Autumn to catch my breath; and start looking into getting a new furnace, water heater, and maybe even replumb the whole house from galv. pipe to PEX.
I hope to semi-FIRE in a couple-three years and start living on my own terms.