Their salty, sweaty, sea hay smell when they come back from the playground; the way they turn on a dime between hating each other and being best friends; the hugs, the kisses, the "I love you's" and nose-rubs before bedtime. Their irrepressible excitement at going fishing, getting wet at the splashpad, building inventions with our recycling, and finding something new growing/crawling/climbing in the backyard. All of these things and so many more bring me joy.
Therefore, it's no coincidence to me that "Boy" rhymes with "Joy". ;)