. >> reporter: michael and ellen robinson, both 38, stopped agrking full-time two year >> i had this that saving as much as we could as early as we could would allow compound interest more time to do the work. >> reporter: how do they all do it? adeney saved 50 to 75% of his o incor nine years as an engineer. >> how much did you wind up saving? >> today would be about $1.1 million or a little bi. that was what we decided was enough to live on forever. >> reporter: adene so-called "4% rule" on his blog: if you salt away and invest 25 times your annual spending in stocks you can then withdraw 4% of your savings each year of retirement. but isn't the market risky? >> put the money in the broad economy through index funds nsere you own thousands of companies, very covative and it's gonna fluctuate just because the stock market fluctuates, but if you're just taking a small amount each year you don't care at all about that like the stock market crashes you're still taking thur little 4%stock market goes up, you're still only taking 4%, soa that as out over time. >> reporter: don't spend mo