Contentment vs Happiness

A long time ago, my therapist told me:
The goal is actually not to be happy, it is to be 
content
happiness dwells on the opposite end of the 
feelings spectrum
Like sadness and anger, it is intense
yet fleeting
Contentment however, lies more in the middle 
more achievable for long periods

I thought about this for awhile
it baffled me
All of these people chasing happiness and
failing because they stepped over
serenity for
exuberance 
with a limited life span