Hawzah News Agency (Qom, Iran) - Here is an excerpt of late Ayatollah Bahjat's guidelines on how to improve one's mental ability and concentration:

Q: What should we do in order to increase the concentration of the mind?

Ayatollah Bahjat: Recite repeatedly the Zhikr (invocations) that are effective in mental clarity, such as ‘Lā Ilāha Illallāh.’ ("There is no deity but God").