Here's the thing with advice: you're always getting it from a biased perspective.
Let's say you want to write a novel. You go out and read the best writing advice that published novelists have to give. They say things like "don't give up" ; "you'll get better with practice" ; "it's all about perseverance" ; "follow your dreams" ; etc.
But these people, they have something in addition to perseverance. Not everyone who tries really hard will succeed; surely there are people who just can't write a novel no matter how much effort they devote to it. Yet you never ask failed novelists, who tried and tried but just didn't have the raw talent, for advice. You go to this biased sample, who say that sticking with it works. Well of course it worked for them; you went to them because they had already succeeded.
This sorta reminds me of when you hear that people who have made some important life decision (e.g., having a certain job, going on some diet) live longer than average. The trick is that "average" includes children, who, sad but true, sometimes die. Thus, anyone who has reached an age where they can make a mature decision (e.g., choosing a job, choosing one's own diet) has already overcome the hurdles of childhood death. Of course the group of people who have made an adult decision live longer (on average) than any similar group that also includes those who died before they were in a position to make that decision. People who watch porn probably live longer than average too.
It may seem like I am being pessimistic, but actually I think this is grounds for a more realistic sort of optimism. This kind of advice is still good, because you will never know if you have the ability to obtain your dreams until you try. It takes perseverance and non-giveuppedness just to discover whether you can do it or not. In other words, these are necessary but not sufficient conditions for success. It's just more realistic to realize that the successful people giving you advice have, by definition, the rest of the sufficient conditions. Conditions you may or may not discover you have by following their advice.
So my advice about advice is to be realistic about advice from people who are already in a position to give you...helpful information.