xvcnmdfs
There's a myth that some people are born with amazing powers (Tesla, Einstein) but what people don't see is the hours they put in from a young age
Therefore, both Tesla and Edison worked hard, except Edison bragged about it
I like the analogue with sleeping: getting into the flow is similar. How do we get to sleep ? We remove all distractions. This has to be the way with focus too.
Another technique is to schedule different periods of the day and different work environments for different kinds of work. For example, if you think well in the morning then reserve the morning to work on all the hard problems of the day and do it in the quietest place you can find (at home, or in a library). Then reserve the afternoon for easy work that's less affected by interruptions and do that in the office.