For most people, including Robert Kiyosaki, income producing assets basically means buying and renting out property. I disagree with doing that on so many levels and also think it's a terrible investment in todays over inflated market.
Another option is to save and make investments, but interest rates are currently so low that it's almost impossible to get escape velocity through low risk investments.
That leaves us with entrepreneurship. That is why we are here and it is probably our best chance, but is never risk free and not a path that the average person will use to build wealth.
This said, building wealth rather than accumulating savings is hard even if you are lucky enough to have all of the necessary ingredients and the right mindset.
Your pillars of health, education and intelligence are important. I'm glad that I have them because whilst I do, I hopefully won't go hungry. They are a safety net. However, I don't think that those alone are a path to building wealth.