Amazon Mechanical Turk is a service that lets you make money online through doing paid microtasks. Each task is something simple that requires human interaction like rating search results, checking for the right spelling on search terms, categorizing the tone of an article, or even basic translating. You can do these tasks from anywhere you want and make money online from the world’s largest e-retailer.
I also participate in online surveys through the following websites, that work in the US and internationally (I use them all and I'm based in Brazil, for example) - Opinion Bureau, Myiyo, and Green Panthera. All of them have a variety of surveys and pay well. All you need to make money is to have 20 min or so to answer a few questions every day/week and have an active Paypal account so you can cash out.
I am also a pragmatic person, so I know that philosophy will only get you so far. If you are at the beginning of your journey here’s what you do. List 10 things you are most passionate about. Then list 10 things you are most skilled in. Rate those from 1 to 10. Then take top 4 (2 best from each side) and try to find the best opportunities. Are there any best sellers in Amazon? Are there any keywords with low keyword difficulty, but large volume of searches? Are there any recurring affiliate commission products? Imagine if you did your absolute favorite thing, and getting paid to do it. That’s what you are aiming for, a “hell yeah”!”
Find a profitable niche. Starting with your interests, write down as many niche ideas as you can. Think about topics people might search online. Ideas include passions (like surfing or body building), fears (like spiders or speaking in front of crowds) and problems (like getting out of debt). Do keyword research to see it others are interested in the topic. Find out if a domain name is available that matches the keyword 100 percent. 
If you want to clear some space out in your house and have a big stack of books you’ve been holding onto for too long, you can make money selling your books and textbooks online. Stores like Half Priced Books and others will give you cents on the dollar for each of your current books while you can check what your book is worth by simply entering the ISBN number on Book Scouter.
Take good pictures. Some of the options below don’t require you to actually take the picture and sell the product, but for the ones that do, make sure you take a clear picture that makes your product stand out from the others. If you’re going to be taking a lot of pictures, set up a small “studio-like” area in your home with a backdrop and proper lighting to really make your pictures come across as professional. And of course, you’ll want a good camera too.
A fitness site can have numerous revenue streams. Create healthy eating plans and recipes and lock them away as premium content. Promote and sell a fitness training course, eBook, or a series of videos. Or advertise your own personal fitness services on your site. Topfithub is a good example of a fitness site with decent video content alongside product reviews.
What’s the catch? None, really. Cash back apps act as affiliates for many online merchants, which means that whenever you make a purchase through one of the apps, they get a small commission — but then, they give you a portion of that commission as “cash back”. For example, if I buy a pair of Nike shoes through the Ebates app (or website) and spend $75, Ebates may get a $10 commission but then they’ll pass $7 back to me. It’s basically a way to get sale prices on stuff that isn’t on sale!