Before, research usually depended on national health surveys in which people often reported their weight as less than it really was.

以前，研究通常依靠美国国家健康调查，但人们在调查中往往会少报体重。

A National Health Survey agrees. After age 30, we become more realistic and do not view happiness as a goal in itself.

30岁过后，我们变得更加实际，不把幸福当成生命本身的一种目标。