I'm forty years old in two months and I'm currently doing my ATPL training. I am on a sponsored scheme otherwise I would not have made the jump from my previous career. I don't think I am finding it any more difficult than the other lads on my course who are nearly half my age, and in fact being older gives you much more of an insight into important skills like teamwork and leadership.
I am realistic about my new career, its work... Its not meant to be fun all the time. You turn up, do as professional a job as you possibly can then you go home to your family and your other interests.
Despite the fact that the profession apparently isn't as good as it was in the 1970's I cant wait to get stuck into flying for an airline...