For certain skill sets, you can do pretty well. In the Navy, at least, surgeons, chaplains, etc go through Officer Development School, aka "Knife and Fork" school where they learn basics like "what the ranks are" and "how to put on a uniform". It's 8 weeks long and while there's a minimum level of fitness expected, they also realize that a 50 year-old isn't going to be doing pushups in the surf. Pay isn't anything to write home about but I've run into doctors who come in as captains making $100k a year. Factor in bonuses and they might be closer to $150k.