Usually when I sit zazen, it's actually very easy. It's also usually pleasant, not that I try to make it pleasant, but frequently it's a rest from automatically acting on thoughts and feelings and instead letting them wave around in space with nothing to drag around. Life is allowed to be very simple, just breath in and out, sounds going around, my back aching or what have you. There is no urgent need to improve anything or fix anything or prevent anything. It's not like going on an exotic vacation or doing anything special, it's like just being at home - the world feels very friendly and instead of assessing each sensory input to gauge whether it's friend or foe, these things don't have to be decided.
I'm always surprised by how good it feels and how peaceful it is - even though I've sat zazen thousands of times. Why do I forget this? Why is it that sometimes many days pass by and I don't sit zazen?