The "secret" is doing it consistently, through good times and bad. You need to consistently save and invest, month after month, year after year, at least 30% of your income. When your account drops 10 - 20%, you need to suck it up and invest more.

A friend of mine is on the FIRE path. The first million took him 15 years (this covered the dot-com boom, bust, great recession, and the recovery that followed.) The 2nd, 6 years. The third, less than 2 years (thanks QE / money printing.)