It's all a matter of habit. A country boy finds it difficult to sleep in the city because there's too much noise. To gain more clarity and wisdom, try saying things out loud. Sometimes you'll see a person walking down the street talking to himself. It's a powerful concentration technique.
Every person has a mantra.
The mantra is your particular music, your individual joy of life. Particularly in learning, there's a certain musical rhythm that draws you deeper into the learning. If you study long enough, you'll get in touch with this tune. It is a tremendous help to get your engine moving. If you're reading, and have difficulty staying focused, start reading slowly out loud and you'll find it brings you right into contact.