One of my all-time favourites

Smile, by Nat King Cole

Smile though your heart is aching
Smile even though its breaking
When there are clouds in the sky, youll get by
If you smile through your fear and sorrow
Smile and maybe tomorrow
Youll see the sun come shining through for you

Light up your face with gladness
Hide every trace of sadness
Although a tear may be ever so near
Thats the time you must keep on trying
Smile, whats the use of crying?
Youll find that life is still worthwhile
If you just smile