The 5 categories of mental chatter

“For most of us, our minds are a little bit dull. If only there were a mind-sharpener we could stick our heads into.” 

~Richard Freeman

In my attempts to be more mindful, I’ve been thinking about the 5 categories of mental chatter (vrttis) discussed in the Yoga Sutras (chapter I, verse 6):

1. Right knowledge: a mental image correctly based on facts (i.e. you see a car and make a mental image of a car)
2. Wrong knowledge: a mental image incorrectly based on facts (i.e. you see a mirage in desert and think it's water)
3. Imagination: a creation of the mind (i.e. reading a novel, making up a story, daydreams)
4. Sleep: absence of content in the mind (your mind is working but you don’t remember it)
5. Memory: mind re-experiencing previous experiences 

These 5 categories are meant to describe all of the mental images we are ever going to have! 

I’ve been trying to categorize my mental chatter as it comes up during practice... and yes, so far seems that each one can be classified under one of those 5 categories (most distracting thoughts are re-runs of imagination and memory). 

The questions is: how do we quiet these down? According to the Sutras, the answer lies in this (chapter I, verse 12):

Persistent practice and non-attachment... might be the closest we have to a "mind-sharpener."