Lil BUB is one of the most famous cats on the internet, thanks to her wide-eyed appearance and chill attitude. Her life wasn't always a stream film fests and hanging out with celebrity friends, though. As a 1-year-old, she was expected to never even be able to walk. Way to show 'em, BUB.

In the latest Lil BUB video, we learn of how, as a kitten, BUB was diagnosed with osteopetrosis, a rare disease that causes bones to be overly dense and prone to breakage. Vets initially thought that nothing could be done to help her, but through physical therapy, her owner Mike Bridavsky's devotion and "BUB's fierce determination," she was eventually able to crawl, then walk, then run. Eventually, she was even able to climb stairs.

Today, Lil BUB — the kitten that almost everyone gave up on — is the guest CEO of the ASPCA. Started as the runt of a feral cat litter in Indiana and now she's here.