Hello Bcoz of the breed

He is a golden retriever

He even doesn't likes to eat he sleeps all the day

I also have golden retriever he is super active go for a normal check up..

There could be many reasons for this. Could be because of illness, disease, lack of activity, or even something else. Ideally, you should take him for walks if you are already not. 2 short walks a day should be fine to meet his activity requirements. Enrichment, physical as well as mental, is essential for all dogs, otherwise they tend to become lethargic and inactive. If the dog is showing some other symptoms, it is advisable to consult your veterinarian.