The statement conveyed exactly the right message as written, it just takes a thoughtful person to understand, someone who is reading to quickly might miss the point.
The original sentence in the article was correct. Here's a positive thought...take an English class!
Perhaps they should rewrite that I too misread it as replace your positive thoughts with negative ones
I believe you misread the statement. Substitute positive thoughts for negative ones, meaning, bring on the positive thinking.
I really like the point: Substitute positive thoughts for negative ones.
I am always having so many positive thoughts that I should start replacing them with negative thoughts. Change is always good. So why not give it a try? Negative thoughts.