Sentence:  The proper fans might also expend time - about twenty hours - trying to visit every Tube station as quickly as possible. [...] But to visit every station in "record time" - which people have been attempting since at least 1960 - requires real <WSD>fortitude</WSD>. You must get up before dawn, you must drink or eat almost nothing, so niggardly is the Underground with toilet provision. 
Meaning of the word marked with <WSD> tags:  Mental or emotional strength that enables courage in the face of adversity.