This is very do-able - I hit the $800k at 40, with 2 children in tow as well as a spouse. You may actually be able to do better (I'm now 52).

I am currently working on a MBA so I can part-time teach in my 'retirement' just to keep active. Be sure to plan something in your retirement - boredom is not good or fun!

I'm still working full-time, mostly because I like what I do, but I am a contractor, and can jump out at any time.

My youngest starts college in the fall, and has some very nice scholarships that should pay for 50-75% of her education, rest will be out of my pocket so she can graduate free and clear. My parents saved only for the older ones in my family, so I had to struggle - something I don't want her to have to deal with too much. Grad school will be on her dime, undergrad on mine.

Good luck - sounds like you have a good sense of fiscal responsibility.