You can't hack flow. You definitely cannot aim for mindfulness. All these are classic cart-before-the-horse conditions. Such flawed notions may sell books, but they don't resolve inner conflicts.
There's a paradox at the heart of this that is difficult to grasp but is true nonetheless.
Joshu asked Nansen: What is the path?
Nansen replied: Your everyday mind is the path.
Joshu: How does one attain it?
Nansen: When you try to attain you fail.