For many people, toiling for a living isn't fun. There can be lengthy commutes, dress codes, annoying coworkers, unreasonable supervisors, taxing physical labor, insufficient vacation time, heavy workloads, and a lack of appreciation, among many other things.

Thus, it's easy to dream of money just arriving, without our having to clock in to earn it. Fortunately, passive income streams don't have to be a dream. There are many sources, with examples including REIT dividend income, residual money, real-estate investments, interest, and other income-generating assets. Here's a look at 15 of them -- see which opportunities could work for you.

red mailbox stuffed with hundred dollar bills that are almost spilling out

Image source: Getty Images.

1. Stock dividends

One of the simplest ways to enjoy passive income streams is to buy stock in healthy and growing companies that pay dividends. Better still, look for dividends that have been increased regularly at a good clip (many companies often hike their payouts annually) and that have room for further growth, as evidenced by a dividend payout ratio of around 70% or less. The payout ratio is the amount of the annual dividend divided by the trailing 12 months' earnings per share. It reflects the portion of earnings being paid out in dividends. The lower the ratio, the more room for growth. A ratio above 100% means the company is paying out more than it earns, which isn't too sustainable. Here are some examples of stocks you might consider and research further:

Stock

Recent Dividend Yield

AT&T

5.3%

National Grid

5%

Duke Energy

4.5%

Verizon Communications

4.5%

Pfizer 

3.7%

Flowers Foods

3.5%

General Motors 

3.4%

China Mobile 

3%

Data source: Yahoo! Finance.

2. REIT dividends

Another kind of dividend to collect is from real estate investment trusts, or REITs. They're companies that own real-estate-related assets, such as apartments, office buildings, shopping centers, medical buildings, storage units, and so on -- and they are required to pay out at least 90% of their earnings as dividends. They aim to keep their occupancy rates high, collect rents from tenants, and then reward shareholders with much of that income. If you're interested in real estate as a way to make money, check out these examples of REITs to consider as investments:

REIT

Property Focus

Recent Dividend Yield

Iron Mountain

Document storage

6.6%

Welltower 

Healthcare

5.9%

Realty Income 

Retail

5%

Public Storage

Storage units

4.1%

Host Hotels and Resorts

Hotels

3.9%

Digital Realty Trust

Data centers

3.5%

Data source: Yahoo! Finance.

3. Stock appreciation

Another way to wring income out of stocks, even if they don't pay dividends, is to buy stocks that you expect will appreciate in value over time and then, when you need income, sell some shares. If you have a fat portfolio of such stocks when you retire, you might sell some shares every year to create a cash stream for yourself. Studying and choosing the stocks that will perform very well for you is easier said than done, though, so if you don't have the interest, skills, or time to become your own stock analyst, consider simply investing in a low-fee broad-market index fund or two, such as one based on the S&P 500. Here's how much you might accumulate over several periods if your investments average 8% average annual growth:

Growing at 8% for

$5,000 invested annually

$10,000 invested annually

$15,000 invested annually

10 years

$78,227

$156,455

$234,682

15 years

$146,621

$293,243

$439,864

20 years

$247,115

$494,229

$741,344

25 years

$394,772

$789,544

$1.2 million

30 years

$611,729

$1.2 million

$1.8 million

Calculations by author.

4. Interest

Among the many passive-income opportunities that exist, interest is a very popular one, along with dividends. Unfortunately, we've been living in an environment of ultra-low interest rates for many years now, so even a savings account with $100,000 in it might only grow by $1,000 or $2,000 per year. Interest rates seem to be rising, though, so take heart -- and know that in many past years, bank accounts and CDs and bonds have paid rates of 5%, 8%, and even 10% or more.

torso of man in suit holding out a stuffed burlap bag with a dollar sign on it

Image source: Getty Images.

5. Annuities

While stocks are terrific income producers, they can be volatile. Every few years, the stock market tends to stagnate or drop for a while before recovering, and that can be problematic if you were counting on your stocks having a certain value at a certain time. One way to lock in an income stream is by buying a fixed annuity (as opposed to variable or indexed annuities, which can have steep fees and overly restrictive terms). Annuity contracts will be more generous when interest rates are higher, but here's how much income they might deliver at recent rates:

Person/People

Cost

Monthly Income

Annual Income Equivalent

65-year-old man

$100,000

$541

$6,492

70-year-old man

$100,000

$620

$7,440

70-year-old woman

$100,000

$579

$6,948

65-year-old couple

$200,000

$921

$11,052

70-year-old couple

$200,000

$1,019

$12,228

75-year-old couple

$200,000

$1,160

$13,920

Data source: immediateannuities.com.

6. Rental property income

Income-generating assets are another of many passive-income opportunities. A classic example is making money in real estate via owning rental properties. It can seem perfect: You buy an apartment building or house, rent it out, and then sit back and collect checks every month from your tenants. The reality isn't always so rosy, though. For one thing, you'll need to maintain and repair the property, as well as paying taxes on it and insuring it. It may not always be occupied, either. You may have trouble finding tenants, or finding tenants who pay their rent reliably. Some tenants may damage the property, and others may be hard to get rid of. You'll be the one they call in the middle of the night if the roof is leaking, and you'll have to clean and perhaps freshen up the property between tenants. You can outsource much of this to a property management company, but it will take a cut of your income, often about 10%.

7. Pay off debt

You might not think of paying down debt as an income-generating activity, but it kind of is. Think of it this way: If you owe $10,000 and are paying 20% interest on it, that's $2,000 in interest payments annually. Ouch. Pay off that $10,000, though, and you'll be keeping that $2,000 in your pocket. It's very much like earning a guaranteed 20% return on the debt that you retire, and 20% annual returns are way more than you can expect from the stock market or elsewhere. Note that some credit cards may be charging you 25% or even 30% interest, so paying such debt off as soon as possible is a no-brainer financial goal.

the word free created in 3-d with dollar bills

Collecting cash back and rewards from credit cards is like getting free money. Image source: Getty Images.

8. Credit card rewards

Speaking of credit cards, if you don't use them to rack up debt, you can instead use them to generate income streams for you -- via their cash-back or rewards programs. Some cards offer flat-rate cash-back percentages up to about 2%. Others target certain kinds of spending or certain retailers. If you spend a lot at Amazon.com, for example, you can get a card that rewards you with 5% cash back there -- which can really add up. (It's not hard to spend $250 per month at Amazon, which is $3,000 per year -- enough to earn $150 back.)

Other stores with associated credit cards include Target, Costco, Gap, Lowe's, TJX, Toys R Us, and Wal-Mart. Many offer 3% to 5% in cash back or discounted prices, and many offer other perks, too, such as free shipping on items purchased at the sponsoring retailer, while others might let you return items without a receipt, or will donate money to charity whenever you use the card. If you travel a lot, you can use travel-related credit cards to rack up lots of points and rewards that can be used instead of cash, keeping more cash in your pocket.

9. Residual and royalty income

You can also generate residual and royalty income for yourself by producing things that might then pay you again and again. This isn't 100% passive income, as there's some initial work involved, but if all goes well, once you've done the work, you'll be paid repeatedly over a possibly long period of time.

For example, you might take photos and have them available for a fee at sites such as shutterstock.com or istockphoto.com. Similarly, you can create and upload designs at sites such as zazzle.com and cafepress.com, where people can buy them imprinted on shirts, mugs, and so on. Similarly, if you write an e-book (which can be as short as 6,000 or so words), you might find that people are interested in buying it, perhaps via Amazon.com's direct publishing service.

10. Sell stuff online

Speaking of selling stuff online, that's another mostly passive way to generate income. You could generate an income stream for a while by clearing out your basement or attic and selling items on eBay or elsewhere. This can be especially effective with collections. If you have lots of games or jigsaw puzzles that are taking up space and not being used, they can be great sources of income. You might reap a lot by selling new and used clothing you don't need.

small model house sitting on a fat pile of currency

Get more value out of your home by renting out space in it. Image source: Getty Images.

11. Rent out space in your home

Not everyone is eager to do this, but consider renting out space in your home for extra income. You could take in a full-time boarder, for example, but you needn't be that extreme. Instead, consider renting out an extra room via a service such as airbnb.com or homewaway.com. If you do so for just 20 nights a year and charge $100 per night, that's $2,000 in pre-tax income! If your home is in a desirable spot, maybe you can rent out the whole house for just two weeks in the summer, charging $2,000 per week and collecting $4,000.

12. Lend money

Here's an option that's still unfamiliar to many people but that has been growing in popularity: Lending money on a peer-to-peer basis. A major website for this is lendingclub.com, where investors have earned returns in the neighborhood of 4% or more annually. You'll be lending money to fellow individuals who have had trouble borrowing money through other avenues, and you can spread your dollars across many such folks to reduce the risk.

13. Refinance your mortgage

Refinancing your mortgage is a passive income generator? Yup, it sure can be. If you're making monthly mortgage payments of $1,600 now, and you can reduce that to $1,300 per month by refinancing your home loan at a lower interest rate, you'll keep $300 in your pocket each month. Of course, refinancing isn't free -- there are closing costs. Still, if you plan to stay in your home long enough to more than break even, refinancing is well worth it. As an example, if your closing costs are $6,000 and you're saving $300 per month, you'll break even in 20 months -- less than two years!

14. Get a reverse mortgage

Refinancing may not be worth it to you, depending on your situation and interest rates, but maybe a reverse mortgage is just what you need. It's typically an option well worth considering for those in or near retirement. A reverse mortgage is essentially a loan, with the amount borrowed not having to be repaid until you die, sell your home, or stop living in it (perhaps because you moved to a nursing home or died). At that time, the home can be sold to cover the debt -- or your heirs can pay it off and keep the home. Reverse-mortgage income is often tax-free, which is another big plus. The amount you get can be delivered in monthly installments, providing very passive and reliable income in retirement.

15. Affiliate marketing

If you have a blog or some other property that has visitors, you might profit passively via affiliate advertising. For example, imagine that you write a blog about movies. You might review some books about movies, and then link to them on Amazon so you get a cut of the purchase price when anyone buys books through the links. If you blog about hiking, you might promote some hiking gear you recommend on the blog, again generating passive income if anyone buys any of it.

These are some of the main ways to earn passive income for yourself. There are others that you can find by doing further online exploration. (For example, you might agree to have your car wrapped in an advertising message and then collect cash just for driving around town in your own vehicle.)

Consider some of the ideas above, because the income they offer might significantly improve your retirement or help you achieve other important financial goals. Some of them might even turn out to be fun.

John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Selena Maranjian owns shares of Amazon, Costco Wholesale, National Grid, Realty Income, and Verizon Communications. The Motley Fool owns shares of and recommends Amazon, eBay, National Grid, and Verizon Communications. The Motley Fool recommends Costco Wholesale, Lowe's, The TJX Companies, and Welltower. The Motley Fool has a disclosure policy.