How is a soul eternally present?

Lalwani explains the 12th verse of chapter 2 of Bhagavad Gita for happiness. Krishna tells Arjuna that there was a time when we all were not there, and in the future, there will be a time when we are no longer there. However, their individuality will always remain there. Hence, there is no need to grieve any of these individuals here because the soul is eternally present.