唯一阻止我去健身房的只是懒惰。

The only thing stopping me from getting to the gym is ___laziness.

抱歉我之前没给你写信——真的没有借口，只是懒惰。

Sorry I haven't dropped you a line before now - no excuses really, just ___laziness.

他的懒惰使他未能按时完成项目。

His ___laziness prevented him from completing the project on time.