I am 36 and love what I do. I'm a little different though as I got my first job programming when I was 16, so I've been doing Software Development for 20+ years. I've programmed in so many languages that it's almost a blur now. I've had jobs writing x86 ASM, Pascal, C/C++, Java, Python, and more. I've been a CTO, but, I loved the coding too much so I'm happy as a Software Architect for a major internet company. Who says you can't code at 36 or 40?
I don't think it really matters when you start, it's how well you do it. I've hired people of all ages, genders, ethnicities because they can code, not because of who they are. You will likely have some issues with your resume as you start out as people will say "Oh, he was just a NOC guy for the last 10 years..." type of thing and pass. But, prove them wrong and show results. Give example websites and have specific examples of the work that you did.
A lot of companies now days hire people who don't know what TCP/IP or a port is, yet, they claim to be web developers. If you have one thing, it's experience with the software domain and you are going to be able to look at problems differently than somebody out of college. Use this to your advantage.
Best of luck and welcome to the joy and pain that is programming!