The easiest way to access flow.
Do you want more access to flow state?
Increase your capacity to feel in real time.
For every moment you can stay present, that's a moment of spiritual/emotional strength training that will make tapping into flow state easier later on.
Being present is vulnerable. It means letting go of being ten steps ahead of everyone else, and it means dropping off any story you might have about how things used to be. It means softening reactivity (judgment, control, justification, righteousness, etc <--- these things are trying to keep us from being present) into present responsiveness.
And remember: presence is a practice, not a state. You can't build muscle if you don't go to the gym regularly.