There's some of that in Kierkegaard, but primarily it's:
1. Existing is in movement. There is only forward. You aren't asked whether you want to be in this world, you are in it. There is no going back.
2. You are alone. There is only you, death and (from a religious perspective) God. 'Indirect communication' is possible, but true communication is not. You cannot save others.
3. Everyone is in despair. Only those who realize it are capable of truly living. Despair is both the road to salvation and the sickness unto death.