**Go green for chilled, red for thrilled. In-between is less extreme.**

Obviously the intent here is to make it short, snappy and catchy via the two rhymes. That second slightly cheesy almost-but-not-quite rhyme could be endearing in a way.
 
This makes it more memorable not just in the context of meaning of the slider, but perhaps also after leaving the site.

As always - try it out with some people and see what they think.