what’s something that took you by surprise as a new puppy owner?

we all know the typical “puppies are lots of work” line but what’s something you were not prepared for as a new puppy owner? or something that took you by surprise in training? for me recently it was the realisation that fetch is not something dogs do instinctively and that they have to be taught to bring the ball back oh - and puppy blues of course…🙃