My dog is getting old I love him so much and I don't want him to go soon😔💔

He's getting really old I know it's a part of life and there's nothing I can do but he was my first pet I'm 20 now and I've had him since I was 7. He was a lost dog and I remember it was raining that day he actually followed me and my sister and we decided to keep him. I cherish every moment with him and I love him and I don't want that day to go soon because muscles are giving up, not very active but I know he still loves me. I wish dogs can just live forever but I know they have to go😔