Bhagavad Gita · Chapter 2: The Path of Understanding

Bhagavad Gita 2.31

svadharmamapi cāvekṣya na vikampitumarhasi | dharmyāddhi yuddhācchreyo'nyatkṣatriyasya na vidyate ||

Looking at your own duty, too, you should not waver. For a warrior there is nothing better than a righteous battle.

Modern context

Svadharma is the duty that follows from who you are and where you stand: your role, your training, your commitments. Arjuna is the protector of his people in a just cause, and that is not a role he can put down in the middle. Each of us has responsibilities that are ours in particular. Note the qualifier: a righteous battle, not any battle.