If you become accustomed to studying at a particular desk, you build up an association between the place, desk, and the studying. Eventually, when you sit down at the desk, you expect to study. Instead, you are almost automatically ready to study when you sit down at the desk. Choose a place to study not associated with another activity. In choosing a regular place to study, be sure you do not select a place that you already associate with a different activity.
Most people have a time limit for how long they can keep their minds on one thing.
This is called attention span. Attention span changes from subject to subject, from book to book, from lecturer to lecturer, and from one time of day to another. People experience peaks and valleys in attention span at different times of the day. Become familiar with your attention span. Read and study during the peaks of your attention span.