Dan, what do you mean by ^context shifting?^ Switching from one problem in a different area to another problem?
I find it easier to do now than I did when I was younger, I see it as just what the job is. When I was younger, a sudden demand to do something different would have me annoyed because it was distracting me from what I really wanted to be working on.
Now I know that everything will be different in 5 or 10 years, so it doesn't really matter what I'm working on as it will be irrelevant soon.
My job requires a ton of rapid context switching, but I do find it much harder now than when I was younger (I am 46).