चित्तस्य साध्यैकपरत्वमेवपुमर्थसिद्धेर्नियमेन कारणम् ।नैवान्यथा सिध्यति साध्यमीष -न्मनःप्रमादे विफलः प्रयत्नः ॥ २१९ ॥
In plain words
An unwavering, single-pointed focus of the mind toward the ultimate goal is the indispensable cause of liberation; it is never achieved otherwise. Even the slightest mental negligence renders all spiritual effort barren.
Close to the Sanskrit
The mind's sole dedication to the goal indeed is invariably the cause of the accomplishment of the human goal. Not otherwise does the goal succeed; upon the slightest mental carelessness, the effort is fruitless.