Question about follow-up amputee

As you know, my 12 year old cat's front leg and shoulder blade were amputated due to osteosarcoma, in July. He recuperated well but he still doesn't want to walk much, although he goes down the stairs with no problem.

Do you have any ideas to make him more active. He used to go for long walks and was a very active cat. (He's an outdoor cat).

Thanks
Andrew

I just answered in your other post, But I would call the vet and ask them to recheck him.