Although it might sound grim, it's helpful to calculate your expected longevity in order to estimate how many years you'll need to have retirementincome for. The further away your retirement is, the more risks you should be willing to take in pursuit of higher returns. In general, this means investing in stocks (and stock mutual funds) when retirement is far away, and a mix of stocks and bonds as retirement approaches. Whenever possible, it usually makes sense for the bond investments to be in a tax-deferredaccount, so that you can avoid paying taxes on the interest earned until you withdraw the income during retirement.