Assuming you want to do this with low risk by the time you're in your 40s, and that you're starting with a net worth of around $10K, you'll have to invest over

Assuming you want to do this with low risk by the time you're in your 40s, and that you're starting with a net worth of around $10K, you'll have to invest over $5K/month and generate an average rate of return of at least 5%/year. If you want to play around with the numbers, there are lots of investment calculators like this one: http://www.bankrate.com/calculators/retirement/investment-goal-calculator.aspx http://www.bankrate.com/calculators/retirement/investment-go...