Counting Crows lead singer Adam Duritz is known for writing intensely personal and introspective songs. That type of songwriting, he says, comes easily to him. But writing an original song for the animated film “Shrek 2″ was not as natural.”I was really struggling with it. I generally don’t write songs on demand, and I almost got to the point where I thought I wasn’t going to do it,” Duritz told Billboard.com. But he persevered, and the finished product, “Accidentally in Love,” is the first single from the “Shrek 2” soundtrack. The 2001 “Shrek” movie and soundtrack are both hard acts to follow: the film grossed more than $266 million at the U.S. box office and “Shrek” became the first movie to win the Academy Award for best animated feature film. Still, Duritz says he did not receive excessive pressure from the film studio to write a hit, and the studio gave him more creative freedom than he had expected.”They just told me that the song had to be uplifting. They actually said, ‘Don’t write a song about Shrek. Write a song that’s about you.’ The funny thing is, the song ended up reflecting a lot of what was going on in my life at the time: falling in love with someone you’re not supposed to fall in love with because it’s inconvenient,” Duritz says.