The real reason is that I started thinking ahead at about 30, and really kicked it into high gear about 40.
No so sure about avoiding interest. DW and I bet heavily on inflation through owning rental real estate, and that has paid off well.
Study the economics and history of inflation. High inflation benefits governments so we will always have it. And it has been with us since before the time of Christ, so it has a long track record.
Save, buy property now with a mortgage you can handle, and pay it back with inflated dollars in the future. Rinse, repeat as often as possible.
I got you beat by 10 years on the retirement age but you did good. Now, do you have any suggestions for that impulse to get back in the work day hunt? You know, wake up to an alarm clock, be stuck in traffic...