Well, I'll bite.
I've worked for the DoD in one capacity or another my entire adult life. Back in 2012 I had an accidetnt at work and broke my right leg/ankle in 16ish places. Lost most of my range of motion and have significant arthritis and swelling in the joint. Sometime in the next few years I'll lose the use of that ankle and have to have it fused at teh joint. I fought and fanagled to stay around this long, against medical advice mind you.
Now I really honestly enjoy what I do, work as hard as I feel like on cool shit. But, my job is contengent on my membership in the National Gaurd. While I can still do my daily .civ job with the best of 'em, I just can't soldier anymore. So, I'll be retired as soon as OPM processes the packet. Decent pension, my 401k has a good enough chunk in it, full bennies for life. My pension is enogh to pay all my bills and then some, just wait for the deposits to hit. But that's not how I'm built. I've got a few other irons in the fire to keep me busy and put more cash in the bank.
That being said, I'm 36 y/o. Got a decent limp and a gnarly scar, can't overexert myself or I cant walk, can't get dehydrated or I can't walk, don't ahve the range of motion to run, or walk up and down hills and all of this will only get worse.
Oh, I have 10 and 6 y/o sons. They are all boy. I can't play any sports with them. Can't take them on real hikes. Can't run cross country with my oldest. Can't do obstacle races with my youngest. These are things I've lost.
Now I'm not crying over any of this. Things happen and you deal. I'm just saying it aint all sunshine and strippers in this early retirement game.