दुःखमित्येव यत्कर्म कायक्लेशभयात्त्यजेत्। स कृत्वा राजसं त्यागं नैव त्यागफलं लभेत् ॥

duḥkham ity eva yat karma kāya-kleśha-bhayāt tyajet sa kṛitvā rājasaṁ tyāgaṁ naiva tyāga-phalaṁ labhet

He who relinquisheth an action from fear of physical suffering, saying "Painful," thus performing a passionate relinquishment, obtaineth not the fruit of relinquishment.

In plain words: Krishna says if you drop a duty because it is hard or might hurt, that kind of giving up comes from restless desire. It brings none of the real benefit of letting go.