If not, why not?
You may have to deliberately seek out sources of humor. Unfortunately life doesn't always mimic the sitcom where fashionably messy homes are inhabited by quick-witted and adorable members. Sometimes life has dirty laundry, grumpy spouses, overtired children, and hormonal teenagers.
That's okay. You can still laugh.
Then I picked up a book, on a whim, and started to laugh. I forgot that I need to laugh!
Suddenly everything is okay again in my world. I have perspective. I feel more relaxed after laughing for a few minutes than I have after the past 2 weeks of yoga. I need to laugh. Every day. And I'm willing to bet, so do you.
Seek out sources of laughter everyday. A book, a show on TV, a website, a blog, maybe even a friend who never fails to entertain. Whatever the source, guard it well and visit it often. If you're laughing, you're alive.