Here's the thing about being in business: you never want to look unprofessional. If you don't think you're in business, look around you. Do you have a job? You're in business. Does someone give you money in exchange for goods and services? You're in business.
There is a level of service expected in business and it is called "professionalism". If you are looking unprofessional, you present the opposite of the level of service expected.
One of the ways I get around this problem is with a todo list. You know those moments when you're working and you think: "I'll just check Facebook or Twitter,"? Those are moments when your mind is wandering and wants something else to do. Chances are you have something else to do. If you aim to be professional, you bloody better have something else to do.