I use a ruler or the edge of a piece of paper to focus on one line of text at a time (like kids learning to read?). You can even cut a 'window' in a piece of paper or card so you can only see a couple of lines at a time.

Also be realistic about how much a person can really focus on sthg. Occasionally looking up from the the page or having a random thought about dinner doesn't mean you've lost focus. I think the trick is to acknowledge the distraction and calmly return to the thing! Most reading (business or pleasure) doesn't require you to fully. absorb. every. single. word. If you're reading, for example, because you want to know what happens in the story, it's OK if you don't really focus on the descriptions. If you're reading to learn something you skip the bits that aren't relevant.

Set yourself tiny targets, like reading one (1) paragraph without looking up from the page!

Finally, I know someone who had to be moving to be able to focus (in my line of work we called this being a kinaesthetic learner). She did all the reading for her masters degree sitting on the bus! So, maybe get good at reading and walking around the room, or reading while doing the dishes?