Financial Goal Question

[Supersetoy]

I know I should probably contact a financial advisor about this...but my goal is to retire by the age of 40. It's going to be tough to accomplish, but I feel like it is attainable.

I just recently turned 23, and every month I have an extra $1500-$1800 to do whatever I want with (this is after bills and putting away 15% to my 401K). I plan on marrying my current girlfriend within the next year and a half, and that number will more than likely raise to $2000-$2500.

What should I do to accomplish my goal? Any comments/ideas are welcome.