Uncertainty doesn't agree with me. I like to plan ahead, but there are only some things we can control.

I may have less than five years to live. Or it could be 10, perhaps 20, years.

I'm 45 and I have a rare progressive autoimmune disease called Scleroderma. It slowly damages my organs, especially my lungs.

Over time, I become more out of breath, a constant reminder that sooner or later my lungs will no longer support life.

I had a close call last year — both lungs collapsed and I was saved by extensive surgery, but there is no stopping the downward progression.

In the early years my prognosis was very poor, considered to be less than five years, so I started preparation for a very early death.

My years working as a nurse, as well as the support of family, helped get me through to where I am today. Still with an uncertain prognosis and health declining, I am stable enough to be able to tell you a little of my story and how the June 19, 2019 changes my life.

From that date, terminally ill Victorians finally have the choice to request assessment for Voluntary Assisted Dying (VAD).

Imagine what it feels like...

Nia Sims before she was diagnosed with scleroderma ( Supplied: Nia Sims )

My condition causes fibrosis and scarring of all of the connective tissues of the body, including skin tendons and ligaments and all the stringy bits that hold us and our vital organs together. It began in my early twenties.

Perhaps you can imagine what that might feel like — hard skin that won't stretch and limits my range of movement, severely deformed hands and toes, hard but brittle lungs which struggle to expand and exchange gases through thickened tissues.

Just going to the toilet or eating causes me shortness of breath. I have a gut which doesn't absorb nutrients well and causes weight loss and malnutrition.

I spend about 16-18 hours each day in bed and perhaps three hours on my feet, short of breath, unable to walk far and with very limited hand movement.

My lungs are failing and could collapse at any time, as they have done before. I have had surgery in the past to patch them up but, ultimately, I am likely to die of slow lung failure (unable to breathe), starvation (unable to receive sustaining nutrition) or slow heart failure.

I have significant disability and chronic pain and live with day-to-day help from my mother.

I also watched my father die a horrific death from brain cancer. I felt helpless watching him writhe in pain in hospital despite what was described as "terminal sedation".

He was never fully sedated in his last days — always visibly and audibly in distress. He lost the ability to communicate several weeks before he died, lost the ability to take food or fluids for at least the last week and was not offered any nutrition, orally or intravenously.

That nightmare has stayed with me.

Peace of mind

Nia Sims has long advocated for voluntary assisted dying. ( ABC News: Madeleine Morris )

Access to VAD assessment allows me to connect in a more meaningful and caring way with my own fragile, crumbling body.

I'm still reminded constantly that my body is letting me down, but I know that when it finally tells me it can no longer support life, I will have the choice to take control and put an end to my suffering on my own terms.

This is a profound freedom of choice for a government to allow its citizens.

The ability to choose a gentle death gives me a new peace of mind — that I won't have to die a long, traumatic death by slow suffocation or starvation.

I may not need to use the voluntary assisted dying medication, but just knowing it is at hand will make it easier for me to breathe with much less fear and anxiety.

If I am in intolerable suffering which cannot be relieved, assessed as eligible, and have life-ending medicine nearby, I will have the comfort of control and choice over when I am ready to end my suffering.

Thank you for listening to my story.