阅读下面短文，从短文后各题所给的四个选项中选出能填入空白处的最佳答案。
Last year, we took a trip to New York City. When we arrived at our 1, it was around 2 a. m. My son, Joseph, looked out at the lights of Times Square and said he wanted to go 2. I told him it was too 3 to go out, but he kept looking out of the window and said, "Just for two minutes."
My wife and I just looked at each other, smiled and said, "Two minutes." We got dressed and walked into the center of Times Square. 4 we got there, my son pointed at the lights and said, "Dad, 5!" And then he started to fall asleep. So we had go back to the hotel.
It took us 20 minutes to 6 for the 20 seconds we spent outside, but it made our son 7 and that meant a lot to us. That night, I learned a lesson about happiness. We sometimes have chances to 8 happy moments in our lives, but we often find 9 to do something else.
Because of my son, I learned that I am the biggest enemy to my own happiness. 10 happiness is a door that is always open, we are the ones who have to decide if we are going to walk through the door.
