In theory, Zen means you do, without thinking. You’re not trying really hard, you just do.
In practice, in order to let go and not try, you have to first try really hard for a long time.
It’s like muscle memory: you’ve done it so many times that your body does it without thinking. The neural pathways are so well worn that you do it without effort or planning. The ball rolls down the deepest channel.
A great stoic philosophy paraphrased: when enduring difficulty we don’t rise to the level of our aspirations, we sink to the level of our training.
So train to be the person you want to be at your most difficult moment.