When you smile you don't only appear to be more likable and courteous, you appear to be more competent.
Everyone knows that Silicon Valley is chock full of fabulous people who do good while doing well.
Children ... smile as many as 400 times per day.
British researchers found that one smile can generate the same level of brain stimulation as up to 2,000 bars of chocolate. The same study found that smiling is as stimulating as receiving up to 16,000 pounds Sterling in cash. That's like 25 grand a smile.