When you read about success or entrepreneurship, you will inevitably read about favors. The common premise is to only do favors that will advance your own cause. Only give your time to those who can give you back something in return. Do something for them now, that will turn into a benefit for you later. These are the opposite of a favor.
A favor is something you do without the expectation of reward. Anything else is a paid service.
You do someone a favor to help them. You use your precious time to do something for someone else. You inconvenience yourself a bit for the sake of someone else. That's what a favor is.
When you do something for someone only when it is convenient for you, that's not a favor.