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Dr. Ian Davis has a fatal disease that has weakened his brain and body, but three years after his diagnosis, he’s not letting the disease stand in the way of his relationship with his new son.

Motor neuron diseases (MND) are a group of progressive neurological disorders that destroy motor neurons in the brain and spinal cord, according to the National Institutes of Health (NIH). With these disruptions between motor neurons and muscles, the muscles do not work properly, which gradually leads to weakening and wasting. There’s no cure for the disease.

When Davis was diagnosed with amyotrophic lateral sclerosis (ALS)— also called Lou Gehrig’s disease or classical motor neuron disease— he was given 3-5 years to live. ALS is a progressive, ultimately fatal disorder that disrupts signals to all voluntary muscles. According to NIH, many doctors use the terms motor neuron disease and ALS interchangeably.

To make the most of the time he has left, Davis, of Melbourne, Australia, records a video of himself reading a book every night for his newborn son, Archie. He’s recorded videos for books including Dr. Seuss’s “Green Eggs and Ham” and “How to Catch a Star.”

As a doctor, he had been researching a cure for leukemia, but as he can no longer work, he is now focusing on other goals.

“I’ve still got big dreams,” he told Australia’s 60 Minutes .

A few items he’s ticked off his bucket list: performing on stage with Pearl Jam, going paragliding and completing a tandem bike ride from Brisbane to Sydney. In 2013, Davis completed a “Million Metres for MND” bike ride— using only his arms— and raised over AU$80,000 for MND research. He successfully launched a beer called Cavalier Courage, which raises awareness and funds for research.

Davis is also connected with Team Gleason, former NFL player Steve Gleason’s foundation for those with ALS, which the former New Orleans Saints’ player was diagnosed with in 2011.

“Besides sharing a diagnosis of ALS, Steve and I are close friends and collaborate to raise awareness and funds internationally,” Davis told FoxNews.com by email.

While it’s become more difficult to read to his son, Archie, as his voice fades, Davis is grateful he’s been able to spend time with him. Since his diagnosis, he has dedicated his life to creating special moments with his family and raising money for motor neuron disease research.

Davis founded the Cure for MND Foundation, a nonprofit that aims to raise awareness and funds for research at the Florey Institute Melbourne.

MNDs occur in adults and children; more commonly in men than women, with symptoms appearing after age 40.

Click for more from the Cure for MND Foundation.

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FoxNews.com's Nicole Kwan contributed to this report.