Laughter graces our very first days. Babies laugh long before they can speak, giggling in their cribs. The average kid laughs 300 times a day: walk through the halls of any elementary school if you need proof of this. But as we get older, we laugh less, considerably less. On average, an adult laughs a mere 15 times a day. This represents a 95% reduction from the glory days of childhood.

Where does the laughter go? Why do we stop enjoying ourselves? Is life not funny anymore, once we hit thirty? Some people think it's because adult life is too full of stress and problems to laugh: what's funny, after all, about work and family and taking care of the car and the dog and the house? But humor can help with all of that. Experts regard humor as one of the most effective forms of stress relief available. So why aren't we laughing?

One of the reasons we don't do things -- any thing -- is that we're afraid. We're afraid of being bitten, so we don't pet the dog. We're afraid of being rejected, so we don't ask the pretty girl or handsome guy out. We're afraid of getting audited, so we don't underreport our income every April 15. Every action has a potentially negative consequence, and it's fear of those consequences that keep us from acting.

What are we afraid of when we don't laugh? Here are the top three fears, things that make people hold in the laughs -- even when they want to.

Fear of Being Unique: The hardest thing to do can be being the first person to laugh: laugh at a joke, laugh at a funny situation, laugh at frustrating circumstances. What if no one else laughs? The fear of being the only one laughing, the only one who has a perspective different from the rest of the group, silences many people who would otherwise laugh. Look at how many people join in the humor after someone else has 'broken the ice': they saw the humor in the situation as well, but were reluctant to laugh until someone else went first.

This is a grown up job, act like a grown up! College days and kidding around at the sandwich shop are far behind you: now you've got a grown up career, with grown up responsibilities. This requires being serious at all times -- which is too bad, since laughter can have positive effects on the workplace: lifting morale, building teams, increasing efficiency.

I'm not a Mean Girl: Many people, particularly women, have been hurt by the use of humor. It's easy to let biting, cutting sarcasm be used as a weapon -- yet it is seldom appropriate. Humor can be uplifting and positive, lifting the spirits of everyone around you. Focus on the funny and forgo the insults and slights: you'll see positive results immediately and you won't have to worry about being seen as "mean".