I read somewhere "The neutral state between pleasure & pain is pleasure."
I think the opposite, more pessimistic, view -- "The neutral state between pleasure & pain is pain"-- is more prevalent; especially in western culture.
If we view our neutral state as a pain, we must continually strive to achieve happiness. This leads to the striving -- the need for continual improvement -- that is so ingrained & revered in our culture. (This way of thinking leads to sustainability issues & relates to Straw Dogs' myth-of-progress thesis.)
"Living The paradox is that the foundation for greatness is honoring the small things of the present moment instead of pursuing the idea of greatness." - From the Tolle quote, previous post.
If we can achieve a baseline of pleasure, there's nothing else we need to do.