Tamāla Kṛṣṇa: 48: "Be steadfast in your duty, O Arjuna, and abandon all attachment to success or failure. Such evenness of mind is called yoga (BG 2.48)."
Prabhupāda: This is the explanation of yoga, evenness of mind. Yoga-samatvam ucyate. If you work for Kṛṣṇa, then there is no cause of lamentation or jubilation. Jubilation is there because you are working for Kṛṣṇa, but there is no cause of lamentation. Yoga-sthaḥ kuru karmāṇi, yogaḥ karmasu kauśalam (BG 2.50). That is the secret of activities, how you can very diligently work at the same time you are not entangled with the actions. That is the secret. Go on.