Put a spring in your step as you eek back to work with a cheery backpack. Take Katy Perry’s mini metallic Chanel version and Miley’s early-years Britney-print sack (OMG, W.A.N.T) par exemple, both of which were spotted at Britney’s debut Las Vegas residency gig (double jel). Lift your walk to work and increase your cool cred at the same time. Win.