我这腿不争气，最后一圈我跑不动了。

My legs failed me and I wasn't able to run the last lap.

说起他的那个不争气的儿子，老父亲勃然大怒。

Talking of his disappointing son, the old father flew into a rage.

可我要是因此就堕落那就是我的不争气。

But I would fall so that if I do not live up to expectations.

或许我真的很不争气，屡屡让她失望吧。

Perhaps I really do not disappointing, it has repeatedly let her down.

你不用担心我会抛弃你，除非你自己不争气。

You need not be afraid of my deserting you, unless you give me cause.