I ask because I visited an old landfill we own and the guys maintaining it are "retired" but on contract. They're in their early and mid 70s. They are both civil engineers and visit the place (15 miles from one guy's house, 2 miles from the other's) 1-2 times a week. I asked the one guy if it was the best retirement gig ever and he said yes, it gets him outdoors, he has to use his engineering skills, and give him cash money.