बल बुद्धि विद्या देहु मोहिं, हरहु कलेश विकार॥ It can be up to you; there's no distinct rule to reciting Hanuman Chalisa. The greater you repeat, the greater you turn out to be near to Lord Hanuman. Your brain really should always be 100% focused on the Chalisa even https://www.youtube.com/watch?v=ufkmD95y7fE