Your retirement investment needs to at least grow by 3%/a in order to mean anything. Even then, it won't mean shit years from now.
Just to give you a small idea...I'm 42. I live in one of the lowest COL areas in the US. $40k is poverty money here NOW. What thee fuck you think $40k is going to get you years from now? Retiring at 42 might sound neat...but the reality is you are still 3 years away from peaking out on your salary. That's $375k for basically pressing palms and looking at young secretaries all day. The majority of my work isn't work at all, and I get paid well for it.
Houses? I have 5. All of them pay for themselves, and the rentals pay most of my main mortgage.
Retiring at 42 is such a dumb idea. You should be relaxing, not retiring.