I read a book for a solid 70 pages, then I get bored and don't read it. What should I do?

Example is: I am reading a book on big bang and God, I get tired of it after reading for like 70 pages, 1–2 pages every day. After this, it becomes a chore.

Another example is: I am reading Richard Dawkins book: The Greatest Show on Earth. After reading for like 144 pages, I lose interest. And normally I am interested in these topics. What should I do.

I have ADHD, if that's important.