Here’s a fashion riddle for you. What keeps tabs on your day-to-day activities (the number of steps you take, the calories you burn) and helps you sleep by tracking your snooze cycle? What wakes you up… with a silent alarm? And offers you personalized stats — plus connects you with a social circle of friends? Meet the Fitbit Flex — and the new Tory Burch for Fitbit collection, which does all this in the guise of a super-chic accessory, like the above gold fretwork bracelet. Get fit, in style.