What do you do when you really can't focus?

Usually I’m pretty good about keeping myself focused, especially when it comes to schoolwork however lately and more importantly right now I just cannot seem to keep my attention on what I need to be doing for more than a few moments.
Sometimes this happens when I’m reading something that I’m uninterested in but right now that isn’t the case. I’m literally staring at the words in my book and not really reading or comprehending what they’re saying. It’s as if I’m just reading a bunch of letters that are all just empty with no meaning.

So what are some things I can do to try to hold my focus on something for more than a minute?
To do lists aren’t helping me either, just so you know!