If you're having trouble seeing the words in a book you may need glasses.
And if you have glasses but are getting headaches or tired eyes while reading, you might need to update your current prescription.
It also helps to read with lots of light around you.
2) Improve Your Body Posture
Poor body posture restricts oxygen, reduces focus, and concentration.
While reading:
• Maintain a straight spine while reading to avoid back pain.
• Keep your head straight and avoid tilting your neck
• Hold the book up a little under eye-level
"Sapiens is the best book of the last decade I have read. He had decades to write Sapiens. There’s lots of great ideas in there and it’s just full of them, chock full per page." -Naval