"I get bored easily and I look for ways for me to be creative," the actor, singer, writer and voice-over artist tells PEOPLE. "I'm always looking for things that are fun and new and exciting."
McCartney, 26, is known for his 2003 hit "Beautiful Soul" and his work on the television shows Army Wives, Greek and Summerland. But did you know he got his start in 1998 on All My Children? Or that he co-wrote Leona Lewis's hit "Bleeding Love"? And what about his time spent voicing video game and cartoon characters including Theodore in the popular Alvin and the Chipmunk films?
"Once in a while, I'll get a 40-year-old gamer and he'll say, 'I love that video game you did for the Japanese. I've spent 80 hours playing it,' " says McCartney. "And in the next room there'll be a 15-year-old girl who is a fan."
McCartney – whose new EP In Technicolor, Part 1 dropped Tuesday – is extremely proud of his varied resumé and appreciates that he has fans of different generations.
"I was just doing Toys For Tots at a children's hospital and one of the moms was telling their son, 'Do you remember Jesse? He sang that song 'Beautiful Soul.' But he was probably only 2 years old when it came out," McCartney says. "Then he found out I was Theodore in Alvin and the Chipmunks – I could have written a Grammy-award winning album but that didn't matter."
Adds McCartney, "I think that's cool. Some of the greats in music have been multigenerational artists and that is what I hope to achieve. I want to make music that can be timeless and listened to for decades."