Last prostate exam I had, I told the doc that I felt like I should ask him out for a drink (just kidding around). He didn't find it funny. 
My doctor and I always find it funny. We get through the regular exam, then talk about whatever, then finally have that awkward silence before we finally decide we have to get it over with. :)
I had my first colonoscopy a few years before 50, which was actually lucky as they found polyps that needed removal. I actually did mine without the drugs. I like to tell people that it's because I'm tough, and I didn't want anyone sticking anything up my butt without me knowing what was going on. In actuality my ride home flaked on me late the night before, I couldn't arrange another, and I didn't want to spend all day in the hospital until they decided I was good to drive. One of the nurses said she'd done it without drugs before, so I gave it a shot. Other than a "backed up" feeling throughout the procedure, it wasn't that bad at all. Plus I got to watch everything on the camera and the assisting nurse was way into flyfishing and I got a tip on a good spot. :)
On the being in shape in old age, there's a guy at my gym in his 70's. I think I'm pretty tough doing bench presses with 70lb dumbells at 51. The first time I saw him at the gym was when he sat down next to me and did three sets with 80's like they didn't weigh anything. Also yesterday while out for a walk with my camera, two guys who also appeared to be in their 70's ran past me jogging at a rate that was faster than me when I run. They were also talking it up like they were sitting at rest at a table in a coffee shop.
The worst thing that happened to me after I turned 50 was getting the AARP envelope in the mail.
