Direct answer
Concentration is easier when the environment, task and routine all point in the same direction. Do not rely on motivation alone. Reduce friction before you begin.
Build a start ritual
Use the same desk, water, notebook and first action. Write the single task you will complete in the next block. A clear start cue removes the decision fatigue that often becomes procrastination.
Study by retrieval, not rereading
Close the notes and explain the idea from memory. Answer questions, solve problems and test yourself. Active retrieval reveals what you know and what still needs work.
Protect attention
Put the phone out of reach, close unrelated tabs and decide exactly when the break begins. Short periods of genuine focus are more valuable than long periods of partial attention.
Make progress visible
Finish each block by recording what you completed and what the next first action is. This creates continuity and reduces the effort required to restart later.