If you feel foggy, yawning at your desk, or drinking too much coffee, you're probably overtired, and it is interfering with your ability to concentrate. Scientists hypothesize that a continued lack of sleep might destroy your brain cells.

When your focus feels depleted, it could be because you are juggling too many tasks.

When big and exciting things are happening outside the office - good or bad - it can become challenging to set it aside and focus on your work. Negative news can severely impact your mood. Good news can increase your adrenaline, and when you are too excited, can cause anxiety.