I served in the US military. I was in the Air Force, but my profession was IT, so I spent my whole service working as a sysadmin.
You can officially retire and collect a pension after only 20 years served. I joined at 18, so I retired at 38 years old. Normally, a 20-yr pension isn't enough to fully retire on, but I got a bit messed up during my service. The VA gave me a 100% disability rating, which includes a monthly pay bigger than my pension! Plus. My wife also served and was medically discharged with a 100% disability rating as well. So she gets the same medical benefits and pay as I do (minus a pension).
With all three sources of passive income, we can live without working. We're not rich by any stretch of the imagination, but we pull in enough to live comfortably and have all our basic needs met.
Like I said, I could go back into the IT field and double my current income (or more), but then I'd be stuck working all the time again, and I don't want to do that. The military was a 24/7 gig for 20 years. "Service Before Self" was one of our core values; we always had to prioritize the mission over our personal lives, and we could be recalled to work any time, day or night. So it's nice to actually have some "me time" now, where no one can make me go anywhere or do anything. Not looking to go back to work and give that up so soon.