The brain can keep only one thought or tasks at a time in working memory. This means that the brain was not designed to multitask effectively. Multitasking involves rapidly alternating shifts of attention from one task to another. Sanjay Gupta MD points out that likely you aren’t actually doing multiple tasks at exactly the same time. You’re just diverting your attention from one part of your brain to another part, which takes time and resources. This can not only fatigue your brain but can increase your risk for making mistakes. Whenever possible, focus on one task to completion, and then work on another one. To save time and brain energy, if you need to get something from another room, say aloud what you are going to get in the other room as you pass through a doorway. This helps keep that thought in working memory. Otherwise, your brain will likely implement its “event boundary” and wipe working memory clean as it passes through a doorway.