Any loss is hard, whether it be a family member or a loved pet. Think of it this way. What would your cat have wanted? Would he want you to sulk and walk around the house doing nothing? Of course not.
He would want you to get in the gym and crush it and make him proud!
When I die, I don't want people to feel sorry for me. I'm dead. I want them to remember the good I brought to their life.
You have my condolences but get back in the gym and crush it buddy!