What are the changes after neutering?

Hi Dear Schnauzer Owners,
Today I have a question for you. I hope you can help me in this regard. We have a 5 months old Miniature Schnauzer Puppy. Next month he will be ready for neutering.
But for the last 2-3 days we are considering whether it will be good for him, or not.
The thing which worries us is that; will neutering change the energy level of our dog? We know that neutrering will calm down the dog, but what is the level of that change. We know two neutered dogs, who literally lost their will to live. They are 3 and 5 years old, and they even don’t like to move. Maybe that is due to their characteristic, I don’t know.
So can you tell me the changes after neutering? What happened to your dogs after they are neutered?
Thank you in advance for your answers. They mean a lot to me…

