Look a little closer at the cut. The real messenger bags are made to wear across the body, not just over one shoulder. I can tell you from personal experience, this works for a whole lotta reasons. I have to work out in 100+ temps, sometimes with high humidity, and these types of bags work, are big enough for all my gear, and the least obtrusive bag type I can imagine. I get real tired of constantly hoisting an overloaded fanny pack everytime I stretch or bend.