Suitcase of Courage

Here's a phrase that I stole it from cycling commentator Paul Sherwen and have been using for a few years. I really enjoy the unusual imagery.

suitcase of courage, noun phrase. A reserve of strength, determination, or bravery that must be called upon, usually by reaching or digging into it, in order to overcome a seemingly insurmountable disadvantage.

Example: Thomas Voeckler is reaching deep into his suitcase of courage as he climbs l'Alpe d'Huez; he wants to stay in the maillot jaune just one day longer.