"Do an act of kindness. Help one person smile"!
Anyone who knows me knows what I think about smiles :)
Never stop smiling, it truely can make a difference... if you're walking down the street and you smile at a complete stranger... do they smile back? If they do even if it's just for a second you spread just a little bit of happiness to them. Smiling keeps you positive, even when things are really bad a little smile can help you cope.
As Sandi Thom said on her album... "Smile it Confuses People"!
P.S. I don't think you should only do kind things once a year but it's nice having a day devoted to acts of kindness and smiles :)