I’ve arrived at the conclusion that I always want to tip better if my wait person smiles and makes me feel comfortable. So I’ve stolen a little from a Nat King Cole classic and written a song for all wait staff:

Smile though your feet are aching
Smile though your back is breaking
Although a tear may be ever so near
That’s the time you must keep on trying
Smile, what’s the use of crying?
You’ll get your tips in a higher pile
If you just smile