Maybe you love your 9-5 job. Maybe it is your absolute dream job and you would feel content continuing exactly as you are 40 hours a week for the next 50 years. Or you dream of the promotion in your future because *then* you will be happy doing a slightly different thing for more money every day for the next 50 years. I have yet to meet many people who say that (business owners and CEOs tend to be the exception because *they* are the boss!) but maybe you fit into this camp.
So here are some questions for you...what if your amazing boss gets replaced with a new boss who makes your life hell? What if your company pushes you to do something unethical? What if you get laid off? What if you haven't gotten a raise or a bonus in the last 5 years and now you feel unappreciated? What if they start chopping away your benefits...*poof* their goes your pension plan, *poof* there goes the 6% match in the company 401k...
It happens. And that's why I think that even if you love your job and you can't see anything changing for the worse, you should STILL push yourself to retire within 10 years (or 15, or 20, or something less than the crazy-but-now-standard 40-50 year mark). Because once that early retirement day hits, guess what? You DON'T have to retire! You can keep working at that job you love, and keep socking away bucket loads of cash until your proper retirement age of 70, or 80, or whatever. You would be a millionaire x 10 easily and what you have done instead of "early retirement" is called "Financial Independence" (FI). If you wanted to, at this point, you could cut back to part time after you have a kid. You could ask your boss for every Friday off because you just don't need all that extra money and you would rather always have a 3 day weekend. If you love some parts of your job but not others, you can ask your boss for more of what you like and less of what you don't. If you get laid off, you will be OK because you were planning to retire anyway! You could quit your job and start your own business. You could choose a new job that gives you a better quality of life and you have the bargaining power to do it!!
There are so many options open to you once you gain FI. All it takes is the ability to live below your means (well below, if possible), only spend the money that you have (i'm a big fan of a budget), and consistently investing the difference.