Jacob Priestley looks forward to his birthday all year long.

Reading birthday cards he’s received gives him a reason to smile.

"It's amazing. I don't know how to explain... it's heartwarming,” Jacob Priestly said.

He turns 15 on August 28. But he faces an uphill battle to get there.

Jacob has mitochondrial disease.

“It’s very tiring. It drains my energy. I’m basically bed-bound,” Jacob said.

The disease shuts down parts of his body, and there's no cure.

"Eventually, it's going to take over the heart,” said Tom Priestley, Jacob’s father.

Jacob has one wish: to receive 100,000 birthday cards.

A stack of well-wishes from all over the country have already come in from all over the world.

"His overall goal is to use his name and who he is...devote his life to try to raise awareness to try to find a cure for it," Tom Priestley said.

At 14, Jacob has already defied the odds. He plans to make each day count.

"We're just going to put a smile on our face, go through life, and say--throw what you got at me because we got each other. We'll get through this,” Jacob’s father said.

They hope that with each card, there’s more awareness of mitochondrial disease and more reason for Jacob to smile.

If you’d like to send a card, the family asks that you address it here:

Jacob Priestley

P.O. Box 855

Queen Creek, AZ 85142