The average child laughs up to 25 times as much as the average adult, who, indeed, is as likely as not to scold giggling youngsters for "being silly." The capacity for hilarity is something most people grow out of once they learn life is full of hard work and disappointment.
It's a shame in more ways than one. Medical research tells us that hearty laughter strengthens the immune system, improves cardiovascular circulation, relaxes tense muscles, and provides many other physical benefits. So if you mix a little humor into your business writing, not only will your contacts like you better for it, but you'll be doing their health a favor.
Beware, however. Being funny is a hard thing to do on command, and not everyone finds the same things laughable. Obscure or offensive humor can be worse than none at all. So when considering how to add chuckles to your writing:
Remember that off-color stories have no place in the business world.
Never make fun of any individual or group. Everyone knows that racial and cultural bigotry are verboten, but prudent writers also avoid jokes that emphasize the presumed failings of mothers-in-law, wives, lawyers, politicians, preachers, and majority groups--or that ostensibly advocate any sort of animal abuse. The idea that choosing a certain vocation or having a married relative automatically makes one impossible or evil is an idea long overdue for a quiet death; and while you have a right to avoid cats if you personally find them repugnant, the ailurophiles among us have a right to be spared the equally repugnant images evoked by "other white meat" remarks.
Never overdo or force humor. Two light remarks per page, or one side-splitter or "groaner" per article, is about right. Since business materials are rarely written purely to entertain, a pun in every paragraph can make readers wonder if you take your main goal seriously. Remember also that a good joke sounds like a natural part of the conversation, not like something plucked at random from the Internet or from a homonym brainstorming exercise.
By now, you may be wondering, "With all these 'don'ts,' what's left?" Probably more than you think. Everyone has some gift for some form of humor, be it puns, exaggeration, deadpan, relevant anecdotes, or simple subtlety. To find where your talent for humor lies, start by noticing when what you say makes your friends or family chuckle.
And remember this almost foolproof principle: A guaranteed laugh-getter is making fun of oneself. While criticizing others makes a person look snide and petty, everybody laughs along with--and respects--someone who admits his own weaknesses. Likewise, the exception to the "don't make fun of groups" rule is the universal foibles of humanity in general ("No one is sure how long the human race has been around, but everyone agrees it is old enough to know better").
May the new business your humor attracts leave you laughing all the way to the bank!