Usher's Advice for Justin Bieber

R&B star Usher has urged his protege Justin Bieber to eat well and take care of himself - to ensure his voice doesn't change too much as he grows into a man.The Yeah! hitmaker has been mentoring the 16 year old since they met in 2008 and they share the same singing coach to keep their vocals in top condition.But Usher has warned the teenager - who pulled out of a gig in New York last month after