The singer returns to her workout routine in London. Plus: Kate Bosworth, Michelle Williams and more

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Hilary Duff casts her musical spell during a performance at a gala benefit for the National Kidney Foundation at the Warner Bros. Studios in Burbank, Calif., on Sunday. Before the event, Duff told PEOPLE, "This last year has been a big year of embracing flaws and accepting who I am – and things that I don't love about myself, I try to embrace them and love them."