Sorry if this is a bit late. The quote comes from the Dec 16, 1893 issue of To-Day, page 18. The full paragraph reads:
ADVICE TO THE NERVOUS
The statistics of influenza have been appearing in the daily papers of late and I suppose that the inevitable results will follow. A number of persons will take an injudicious care of themselves, a selection of the more advertised quack medicines, and a serious fright; subsequently they will be likely to take the influenza. And the man who does his day’s work, takes the average risks, thinks very little about his bodily health, and regards influenza as a complaint and not as a mysterious ghost with its eye upon him in particular, will be much less likely to take it. Nervous cowardice is an invitation to the influenza. Is there any remedy for nervous cowardice? The best remedy is to acquire an interest in anything or anybody except one’s self. Courage depends less upon the individual than upon the individual’s point of view. Eat good dinners and drink good wine; read good novels if you have the leisure and see good plays; fall in love if there is no reason why you should not fall in love; but do not pore over influenza statistics.