Chuang-Tzu: Happiness is the absence of the striving for happiness.

Tim Ferriss: The opposite of happiness is boredom.

Eliezer Yudkowsky: When people complain about the empty meaningless void, it is because they have at least one problem that they aren't thinking about solving — perhaps because they never identified it.

Alex Krupp: Given perfect freedom people have a tendency to do just enough to make themselves minimally happy, even if greater happiness is ultimately attainable.

me: There is no 'minimally happy'. Different things either make you happy or they don't. However, happiness from a source can last a long or short duration, ebb faster or slower.

Paul Graham: Unproductive pleasures pall eventually.

Credit: HN thread on existential angst.