How does your mental health affect your ability to stay focused?

Mental health. Problems with mental health such as anxiety or depression or attention deficit lead to poor concentration & affect your ability to stay focused.
Lots of ways! One of the most common symptoms of mental health issues is insomnia. Just one night of poor sleep will negatively effect you ability to concentrate.
You can lose focus . Any mental disorder that affects you emotionally and functionally can drain energy, and mental clarity, especially when it is chronic. Your ability to stay focused is likely going to be diminished. Contrast that however to what happens to you when you are fearful or suddenly threatened in some fashion and you could be in true danger of harm. All your senses are on hyper alert for fight or flight.