Achieving focus in a movie is easy. Directors can simply point the camera at whatever they want the audience to look at. Close-ups and slow camera shots can emphasize a killer's hand or a character's brief glance of guilt. On stage, focus is much more difficult because the audience is free to look wherever they like. The stage director must gain the audience's attention and direct their eyes to a particular spot or actor. This can be done through lighting, costumes, scenery, voice, and movements. Focus can be gained by simply putting a spotlight on one actor, by having one actor in red and everyone else in gray, or by having one actor move while the others remain still. All these techniques will quickly draw the audience's attention to the actor whom the director wants to be in focus.

Many high school students study and learn inefficiently because they insist on doing their homework while watching TV or listening to loud music. These same students also typically interrupt their studying with repeated phone calls, trips to the kitchen, video games, and Internet surfing. Ironically, students with the greatest need to concentrate when studying are often the ones who surround themselves with the most distractions. These teenagers argue that they can study better with the TV or radio playing. Some professionals actually support their position. They argue that many teenagers can actually study productively under less-than-ideal conditions because they've been exposed repeatedly to "background noise" since early childhood. These educators argue that children have become used to the sounds of the TV, video games, and loud music. They also argue that insisting students turn off the TV or radio when doing homework will not necessarily improve their academic performance. This position is certainly not generally shared, however. Many teachers and learning experts are convinced by their own experiences that students who study in a noisy environment often learn inefficiently.

Humans are champion long‒distance runners. As soon as a person and a chimp start running they both get hot. Chimps quickly overheat; humans do not, because they are much better at shedding body heat. According to one leading theory, ancestral humans lost their hair over successive generations because less hair meant cooler, more effective long‒distance running. That ability let our ancestors outmaneuver and outrun prey. Try wearing a couple of extra jackets—or better yet, fur coats—on a hot humid day and run a mile. Now, take those jackets off and try it again. You'll see what a difference a lack of fur makes.