I'm looking for a word that captures the idea of someone that's about to embark on a challenging pursuit.

"This was his \_\_\_\_"

I'm trying to capture the idea that the pursuit is longer than a moment but not long as if the individual was going on an epic journey.

Words that have the idea of training, camp, pursuit, challenge, test

. It can even be a metaphor. For example, I might say 'His Achilles heel was alcohol'.

Thanks