GENEVA (AP) — A 104-year-old British-born Australian scientist who is planning to kill himself on Thursday says he doesn't think the drugs used for assisted suicide should be available to just anyone, but that doctors should be able to prescribe them.

In an interview Tuesday with The Associated Press just two days before he plans to take advantage of Switzerland's assisted-suicide laws, David Goodall spoke of his determination to end his life. He also talked about his disbelief in the afterlife, his childhood after being born during World War I and his family, who lives across three continents.

Goodall said he's been considering suicide for about 20 years but only started thinking about it for himself after his quality of life deteriorated over the last year.