I guess that all you have to do is focus, don't procrastinate. Shut off anything that might distract you, like put away your phone. Don't even listen to music, because sometimes that just breaks concentration. Considering how you've been trying to study for the past 2 hours, try taking a break. And continue to take short breaks so you don't get too tired!
I hope this helped haha! I've had far too much experience with the same issue.
Because you wouldnt want to state that something is a fact when it is really not.
Answer:
the old age weakens his voice