"This country is my home".
Dr Goodall does not have a terminal illness, but says he wants to take matters into his own hands as his quality of life is continuing to deteriorate as he lost the ability to walk.
Goodall attempted to take his own life a few weeks ago but ended up waking up in hospital instead, where doctors judged that he was a risk to himself.
Exit International director Philip Nitschke says "there is a growing generation of older people who are living longer than ever before, who are not ill, and who are demanding end of life choices".
After having his driver's license revoked at age 94, the esteemed academic and grandfather of 12 said his loss of independence made him want to die. To elect euthanasia in Victoria, a candidate must be terminally ill and less than six months from imminent death.
Goodall, described by the right-to-die group Exit International as its first member, said he tried clumsily to take his life himself at least three times - and then finally chose to get professional help.
I am content, ' he said.
Around midday, an IV was placed into Goodall's arm, allowing him to turn a wheel to let the lethal drugs to flow into his bloodstream, according to Exit International, an Australian nonprofit that advocates for the legalization of euthanasia.
'I am happy to have this chance, though I would have preferred to have had it in Australia, and I greatly regret that Australia is behind Switzerland in this move, and that most countries are in fact behind Switzerland.
Unable to pull himself up, his cries for help went unanswered and he remained on the floor for two days until he was found by his cleaner.
"I called out, but no one could hear me", he said.
His last words before losing consciousness were "this is taking an awfully long time", Nitschke said, but "he died shortly thereafter".
According to a report by USA Today, a friend will go to a Swiss clinic with Goodall, where Goodall will receive a "fatal dose of barbiturates".
The centenarian has already bid goodbye to family members in Australia and France.
During his last press conference Wednesday, he explained his reasons for his big decision.
He said there were things he would miss, such as his "journeys into the Australian countryside".
Even though the 104-year-old Australian scientist is an accomplished man, he did not come to the limelight until in 2016, when the Edith Cowan University, where Goodall worked, controversially sought to eject him.
"At my age, or less than my age, one wants to be free to choose the death when the death is at an appropriate time", Goodall said.
"If I had been asked to provide my own comments on David Goodall, I would have said he is perceptive, brilliant and inventive", said Robert Russon, a 30-year professor at the Logan school in a letter to the Herald Journal newspaper.
"People like Dr Goodall make a decision based on nothing more than they've decided there's nothing more to live for", he said.
When asked by a journalist whether he was certain he wanted to go through with his plan, Dr Goodall laughed and replied: "Oh yes, that's what I'm here for".