Selling blood….there are very few companies that buy your blood. #1 reason being MANY people willing to sell their blood are not the type of people you want to receive their blood, ie drug addicts (not everyone). And if you can find a company willing to buy your blood you can only give it every 56 days (for whole bood). The most common blood product that is bought is plasma and you can only do that every 28 days (in New York state …which won’t buy blood anyways).
Market your course: The beauty of using a course to make money online is that you can continue to sell it for as long as you’d like. Look for niche communities on Facebook, LinkedIn, or Reddit that might benefit from your content. Guest post on relevant blogs and sites. Look for anywhere you might be able to get in front of the right people. With just a few hours a month you can continue to generate sales.