What exercises can I do to increase my attention span?

simple exercise: Read books (physical ones, not eBooks on computer or iPad). Get off the internet and switch off your phone, and spend an hour each day reading books without any distraction. This will teach you to be focused and attentive to what you are reading, and learn to tune off all external stimuli. In turn, this will help your general attention span. Additional benefit: You will also gradually become smarter, assuming that you didn't spend the time reading romance novels or comic books.