This verse lands like a final instruction before the soldier goes to the front line. Krishna says: surrender every action to Me. Act with spiritual awareness. Drop all hope of personal reward. Let go of 'mine.' And then — fight. Do your duty without the fever of worry.
The word 'vigatajvarah' is the quiet gem here. Jvara means fever, the restless burning of anxiety. When you hand over your actions to a higher purpose and let go of both hope and possessiveness, the fever breaks. The mind settles. Not because the situation has changed, but because you have changed your relationship to it.