I overheard a coworker complain to the manager that he was always telling him what to do, while he left me alone. The manager's response was because I always looked busy.
Walk with purpose, and everyone will assume you're doing something important.
My advice to young people at work: put away the cell phones, it makes you look lazy, even if you're just walking. Personally, I try not to look at my phone unless I'm alone in a room.