Firstly, rendezvous means:
1. A meeting place at an agreed time and place, typically between two people
2. A place used for such a meeting
The poem 'I have a Rendezvous with Life' is about accepting that you will die someday but not letting that get in the way of you being convivial and enjoying life. It was inspired by a poem that Alan Seeger wrote called: 'I have a Rendezvous with Death.'
The capital letter on Life personifies life as a person, friend, or an acquaintance.The 'rendezvous' they meet at is a psyschological way of the poet saying 'I will live my life to the fullest' and not hide away from it but rather meet it.
This poem is about "living." Not being afraid to enjoy life.
The following line is very telling:
"Sure some would cry it's better far
To crown their days with sleep
Than face the road, the wind and rain."
This could be modernly interpreted as "Why sleep your life away?" Cullen obviously shows fear for the unknown and admits that, but the fear is not enough for him to avoid and not enjoy life.