A crucial point for the traveler is a kind of an overlapping zone appearing between the physical plane of the Inner Earth (lava, rock etc.) to the etheric plane (the non-material, superior plane above the physical plane).
The level of consciousness must match the etheric plane!
Only if there is a resonance, one can move on. The transition happens gradually and takes some time. Cezar also points out that a strong focus and awareness is needed now. The more advanced the traveler is in his psychic and mental abilities, the less uncomfortable is the passing.