How to prepare for the loss of your dog?

Hi all,

Sorry for the depressing post. But I would really like some insight on how one can prepare for the day you have to let your dog go. And for people to share their experience with me.

I am the proud guardian of a 9 year old wolfdog. I have him since he was a puppy and for the first few years it was just him and me.
I battled a lot with mental health problems at the time which I was able to overcome thanks to him.
So, long story short, we have a pretty amazing bond and he means everything to me.

I have been dreading the day that I will have to say goodbye to him. Right now he is still healthy and very fit for his age, so I really shouldn't worry right now. But I am really scared of the impact his passing will have on my mental health when that day comes.

So, any recommendations, personal experiences, or idea's about how to prepare for this day, will be greatly appreciated.