When you are alone without other human beings, electronic gadgets, food & drinks, internet, entertainments, movies e.t.c. and even circumstances around you are becoming more difficult for you.
Do you find "inner-peace", "joy", "purity(righteous-desires/thoughts)"?
This is what defines *eternal life in Christ Jesus(Kingdom of God)* within any human being
thus "the kingdom of God is not in eating and drinking but righteousness, joy and peace in the Holy Spirit"
{Romans 14:17}