Pack Up Your Troubles In Your Old Kit Bag song lyrics 
WWII songs from www.traditionalmusic.co.uk 
PACK UP YOUR TROUBLES IN YOUR OLD KIT BAG (George Asaf / Felix Powell) Spike Jones & his City Slickers (Vocal: The City Slickers) - 1942 Also recorded by: The Andrews Sisters; Bob Crosby & his Orch.; Lew Davies; Red Foley; Victoria Jackson; Jack Lemmon. 
Pack up your troubles in your old kit bag And smile, smile, smile. Don't let your joy and laughter hear the snag 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. 
(Musical Interlude) 
Pack up your troubles in your old kit bag And smile, smile, smile. Just pucker up and whistle (Whistle) (Whistling) 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. 
(N.B. This is Spike Jones' version. In other versions I've heard, the third line is: "while you've a Lucifer to light your fag"