Hi! Pack up your troubles in your old kit bag,
And smile,smile, smile.
While you've a lucifer to light your fag,
Smile, boys, that's the style.
What's the use of worrying?
It was never worth while, so
Pack up your troubles in your old kit bag,
And smile, smile, smile.

This very popular song of World War I was written by George Asaf (George Powell) in 1915. The music was composed by Felix Powell.