Sankaracarya's Vivekachudamani 434

अतीताननुसन्धानं भविष्यदविचारणम् ।

अउदासीन्यमपि प्राप्तं जीवन्मुक्तस्य लक्षणम् ॥

atītānanusandhānaṃ bhaviṣyadavicāraṇam |

audāsīnyamapi prāptaṃ jīvanmuktasya lakṣaṇam |

(Sankaracarya's Vivekachudamani 434)

No thought for the enjoyments of the past, no thought for the future, and indifference even for the present—this is the indication of a jivan-mukta.

A person who understands the soul which doesn't belong to this world. He will not lament about past, present, and future. Lamenting is not a job of a pure devotee. A surrendered devotee should only leave everything to the Lord's idea. Jivan Mukta will in the trans of the Lord, besides worrying about the material world.