If you refer as knowing that tomorrow is my last day of life, i would:
Call all my friends by phone, by messages, by letters, house by house, and tell them what they brought in my life, what they meant to my existence, and i would ask them one-by-one just a favor: don't forget me, don't forget my experiences with them, phun, sadness, fears or incomprensions so i'll be sure of one think: my presence on the earth will survive myself, and this is a great achievement.