Question

how to read for a long time without getting tired

Answer 1

Study in the early morning ,I think this is the best time to learn more in short duration, Because study for a long time is not possible without habit, first u increase the time period of your study day by day with an increase of 30 min. then in some time you will be able to study for a long time,
don't take your study as a boring activity, find a point of interest in it, then this become helpful for you for a long duration study.

Answer 2

for this our mind is fresh everytime and we are interest in study