Pack up your troubles

We went to Emily's school presentation of this terms work on Friday, they have been studying WWII and Chronicles of Narnia.  One of the songs they sang was Pack up your troubles which originates from WWI.  If the soldiers could do it why can't I?

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 never was worth while, so

Pack up your troubles in your old kit-bag,

And smile, smile, smile.