In all my years of practice, I have found meditation to be the most challenging and frustrating.
I would find my mind wandering and then get angry with myself for letting it wander and that would then spiral into a conversation of 'don't be angry, just let it pass through like clouds in the sky'. That would then turn into 'I wonder what shape that cloud would be, maybe a dinosaur, I love dinosaurs, brontosaurus, stegosaurus, triceratops, tyrannosaurus......
