With age 65, age 40 is the new 35!
That is how I looked at it when deciding to leave a senior position at a regional and going to a major at age 40. I still have 25 years.
Flying for a major is wonderful. Just realize that this career is horribly unstable. I have my dream job, finally flying 757's and 767's, but risk getting set back ten years in a merger arbitration. At my age, the 10 year set back is fatal to my career goals.
The job is great when out of the chocks. When reading the web board, or the Financial Times, it is just awful. Flying, these days, is a much better hobby than it is a profession.
You can have the same fun, maybe more, flying a part time 135 job without the constant ups and downs of a career in aviation. Also, I'd look for an IT job where they have a flight department you can tap in to. My former employer had aircraft I could train in and fly. Some companies and schools have large GA flight departments / clubs. Cessna, Boeing, Georgia Tech, all serve as examples.