What was the number-one song on the day you were born? For me it was “Make It With You” by Bread (US charts) and “The Wonder Of You” by Elvis Presley (UK charts).

According to that page your “life’s theme song” is the number-one tune on the day you turned 18. In my case that’s Steve Winwood’s “Roll With It” (US) and “The Only Way Is Up” by Yazz & Plastic Population (UK). I’ve never heard of that last one, so obviously it provides the theme for my existence on some deep and unknowable level.