What Is That Elusive X Factor?

Making our Family Home Evening treat on Monday--homemade pretzels.  Find the recipe here.  It was great! And so easy.

We complete five weeks of summer today.  Thirty-five days of no school, activities galore, swimming and more swimming, fun, work, rest, play.
And of those thirty-five days, I can honestly say that one of them has been perfect.
Perfect.
I took the four little kids to the Arizona Science Center last Thursday.  Forgot the camera--how could I do such a thing?
I brought the double stroller, plenty of snacks, and an attitude that "This will not turn out the way I planned, just like every other day this summer."  I have never been so happily wrong in my entire life.  My kids played and laughed and watched and learned together.  Hyrum and Micah hugged each other and hid in mock fear from the "hurricane."  Lily helped me and never had a sour attitude.  Evie only ate once, then she was great the rest of the time.
No one cried when it was time to leave, and since it was lunch time, I WANTED to take them to McDonald's for lunch.  No one cried when there were pickles on the bun--they just removed them.  No one cried when it was time for quiet time.  Micah and Hyrum both actually slept, and Lily played at a friend's.  Friends came over for the afternoon, and everyone got along swimmingly in the pool and in the basement.
Ben worked on homework and attended school, just like always, but he willingly babysat the kids while Brad and I had our anniversary date. No one called the cell phone complaining of child labor violations.  Everyone got a bath, clean jammies, clean diapers and full bellies.
We came home to three kids asleep and two kids playing Stratego--all agreed that the night had been "fun."
I went to bed that night saying, "Today was a PERFECT day.  I loved today.  How can I get that again?  What was the formula?  That elusive X factor that made everyone happy all day?"
If you know what it is, please tell me the secret.
If not, I have about 42 days of summer left.  Maybe I'll see one more day like that.  And if I do, I will count myself truly lucky indeed.

My genuine wish for you is one summer day just like this one!

Linking up to Miss Jenny's Alphabe-Thursday X.