muster

He had a horror of destroying documents, especially those which were connected with his past cases, and yet it was only once in every year or two that he would muster energy to docket and arrange them; for, as I have mentioned somewhere in these incoherent memoirs, the outbursts of passionate energy when he performed the remarkable feats with which his name is associated were followed by reactions of lethargy during which he would lie about with his violin and his books, hardly moving save from the sofa to the table.

“Muster up all your courage, then, for never have you required it more.”