My daughter, Emily, at age 4, demonstrated what I believe is possible for all of us, and I wrote "is happy" on my love list to call in a partner who also believes in and practices what's possible. Emily was fussy and whiney in her resistance to take a nap, just like the girl, Jenny, in the story book we’d become accustomed to reading each day at nap time. Jenny, like Emily, didn’t want to take a nap and made it known to her own mother by crying and declaring, “I’m not tired!” Yet, Jenny would eventually become too sleepy and fell asleep, awakening with a pleasant demeanor and exclaiming, “I’m happy now!”One day, as Emily and I finished reading the story about Jenny, I kissed Emily and wished her a good nap. Emily started her daily defiance ritual, crying and complaining that she wasn’t tired. I held firmly to the fact that is was nap time, and Emily relaxed her body on the bed and allowed her eyes to close, for about 5 seconds, when she jumped up to her knees, smiled broadly, and exclaimed, “I’m happy now!”And everything about Emily was happy in an instant. Her face had softened, her voice shifted to sounding pleasant, and the dampness of her tears was the only sign of former suffering. My 4-year old daughter instantly shifted from distress to happiness in just a few seconds. It wasn’t fake. She was happy.I learned that day that humans can make a choice in any moment to be happy. I’ve learned since then that science supports my experience. 'My Stroke of Insight,' by brain scientist Jill Bolte Taylor, is about her recovery from a massive stroke and in it, she explains the physiological mechanism behind emotion. A negative emotion, like anger, is an automatic response and lasts just 90 seconds from the moment it’s triggered until it naturally dissipates from the body. One and a half minutes. That’s it. When negative emotions last any longer, it’s because we’ve chosen to retain to them...to fuel them. So, like Emily demonstrated, we can cling to any emotion we choose, including happiness. I named this characteristic, "is happy," on my list of 100 ideal descriptions to share my life with someone who understand how powerful we humans are: that we can choose in any moment--in a 90-second instant--to be happy.