Ryan Coomber, 4, cuddles with his father Robert. ((CBC))

A youngster who lost his leg in a lawnmower accident last year is now thriving with his prosthetic leg — a testament, his parents say, to Ryan Coomber's resilience and optimism.

Ryan, aged four, was run over last summer by a riding lawnmower near his home in Willow Bunch, Sask. He was seriously injured and his left leg was amputated below the knee.

But today, Ryan is an energetic four-year-old who loves to run around with his older sister and new puppy.

The boy's father, Robert Coomber, says Ryan's positive attitude has been nothing short of amazing. "It could have been 'poor me' and nothing but pain, nothing but sorrow. It could have ruined our family. But it's that smile, that cheerfulness … it keeps us together like glue. It is glue. Ryan is the glue to our family."

Robert said Ryan is so attached to his prosthetic leg he has to wait until his son is asleep to remove it. The leg is bright blue and decorated with images of Ryan's favourite cartoon character.

In the playground, Ryan's mother Amie Rivest can hardly keep up with the energetic youngster.

Ryan will need more surgery as he grows into new prosthetics. His parents say the most important thing is helping Ryan maintain his positive attitude as he grows older.

"I couldn't ask for a happier boy," his father said "And I think that he'll have a bright future if he can keep up that attitude."