definitely too old
Ooops, 40, well now, you know, we all have to be established in our careers by age 25 in order to get ahead and be of any use . . . just look at all the employment fallout from the dot.com industry, all those old folks fired at 30 because they were obsolete.
Less tongue in cheek: I got tired of f/w and seriously moved into rotary a couple of years ago. Decided to take it seriously and moved on up to Flight Instructor this summer, almost instantaneously took a position as Chief Flight Instructor for a fair-sized school in Florida. Soon CFII-H. But you can't be doing this sort of thing when you get old, quite improper, takes the money out of REAL workers' mouths, etc.
Oh, by the way, I recently turned 66. And I do this for fun (although they ALSO pay me fairly well), having already made retirement in the corporate f/w jet world.