thinking too much is a scary thought

"Be master of mind rather than mastered by mind." That's exactly what it said. But what exactly does it mean?

I don't know! It would appear to be telling me that intellectual matters are not all there is to life, or are not the way to have a good life ? Or is about fear and loneliness, and all the other things and thoughts that lurk in the dark hollows , and get pushed back by bright lights only to surface when it is quiet, so quiet all you hear is your own? Is it about living life as you truly want, finding what pleases you. Not what you think pleases others? Is it about seeing beyond the spin and the hype? Every question begs another question.