Many retirees lack control over 50% or more of their retirement income. For example, if a retiree has income of $50,000 annually, and $30,000 comes from social security and employer pension, the retiree controls less than half of his retirement income making those sources somewhat useless to discuss. So let's focus on the sources of retirement income you can control and how to boost them.
An important source of retirement income is Interest income. Interest income comes from money you loan. You may loan it to a bank (in the form of savings accounts or term deposits), you can loan it to a company in the form of owning a bond, you can loan it to a local government in the form of owning a municipal bond and you can loan it to a national government, US or otherwise. In all cases, these sources of retirement income you control because you select the instruments to own. Generally, the longer term instruments will pay you higher interest income. For example, if you want to loan your money to the bank for 12 months, don't be upset to earn only 4%. If however you loan you money to IBM for ten years, you may earn 6%--a whopping 50% more in your retirement income.
Of course you may come up with all types of reasons not to lend to IBM--its not as safe as the bank, ten years is too long, etc. but all of these excuses add up to a much smaller paycheck for you.
Dividend income from stocks and mutual funds can be an important and significant source of retirement income. If you own mutual funds, there are funds oriented toward paying a consistent dividend income and those that do not. Are you in the right funds? Similarly, there are value stocks that pay dividends in the 5% neighborhood while many growth stocks pay no dividends at all. By your selection of stocks and funds, you control this important source of retirement income.
Although many retirees don't often think of their retirement income in the following way, they should. Your assets are always a source of retirement income and how much of your assets you "annuitize," i.e. convert to an income stream, is a personal decision that can be the difference between eating filet mignon or dog food. The simplest way to create this source of retirement income is to buy a life annuity from an insurance company. For example, a 70 year old male purchasing a life annuity for $10,000 can expect payments of $8,500 annually for life. Of course, when he dies, the $100,000 is gone. BY purchasing the life annuity, he has converted capital to a source of lifetime income. The immediate annuity calculators will give you an idea of how much retirement income you can obtain in this manner.