I puzzled over the problem for ages before the light suddenly dawned on me.

我对这个问题冥苦想了很久才豁然开朗。

As people grow older, they begin to ruminate on the uncertainty of life.

龄的增长，人们开始对生活的变化无常冥苦想。

He puzzled his brains to find an answer.

他冥苦想寻求答案。