When we are awake, there is always something going on in our mind, in other words, we are always "thinking" about something. 

But if we give it a closer look, not all of these "thinking" are benefiting our lives. Sometimes we are not actually thinking, but just ruminating, which is a waste of time; some other times even if we are  indeed doing some rational thinking, it can be somewhat counterproductive and might produce detrimental effects in our lives if we don't pay attention. 

I hope this episode can help to ring a bell. 

Let's all learn to be good thinkers, instead of wasting our time on pointless thinking.