First, a lot of this is in the abstract and the difficult part is how it gets applied in any given situation. For example, there's a lot in it about "successful people maintain a belief in control" but then also a lot about "being able to shift goals is important." Those aren't mutually exclusive, but they can often be in practice, and that conflict of choices is where the true difficulty is.
Second, these sorts of things often have nothing to say about goals or values. That is, it assumes there's some "success" that's implicitly known and agreed to. For example, profit, or holding a certain position or something of that sort. That's all well and good if you are on board with that being your goal, but what happens when your ultimate goal comes into question? What if you get to a certain point and realize that progressing further conflicts with your ethical values? What if you realize that you're on a track that doesn't appeal to you for whatever reason? I think these types of questions are often the most tricky ones.
I'm not saying this sort of text isn't useful -- on the contrary, I would have liked to read this long ago. But often times the sorts of dilemmas people face are one thing dressed up as another.