Pop star JUSTIN TIMBERLAKE struggles to write his own songs because the process is too time consuming to fit into his busy lifestyle.

The CRY ME A RIVER hitmaker instead prefers a more spontaneous approach to making music.

He says, "I have trouble writing, it slows me down. I go into the studio and come up with an idea, then bounce it off of whoever I'm working with or if I'm by myself, sit down at the piano and start banging it out."