How has having a pet changed your life?

I have a small family of guppy fish at home and they're literally the sunshine to my days. I can't even think about an empty space at home where my Aquarium is situated. I've also been an owner of a cat in the past who hugely helped with alleviating depression and anxiety during those times. I sadly had to give him away when I went off to college and I couldn't take him with me. Right now, I'm financially not at a place to bring a pet home and give it the attention and love it deserves. What do you think? Have you ever got a pet and it changed your life?