Verse 18

प्रविचार्य स्वसंस्थेन स्वस्थेन स्वेन चेतसा ।तिष्ठन्ति विगतोद्वेगं सन्तः प्रकृतकर्मसु

In plain words

Having inquired thoroughly, with a mind of their own that abides in itself and is at ease within itself, the good remain, their agitation gone, in the actions that come to them in the ordinary course.