The idea is that intelligent people have a strong tendency to discount motivational platitudes and self-help books, because those sound (and often are) stupid.

There's a book, "59 Seconds" by psychologist Richard Wiseman, which examines a lot of common self-help claims by looking at actual studies. He shows how many are wrong or are actively harmful. However, the book also has quick tidbits of actually productive things one can do that are comparatively minor. People interested in these issues should read the book.