Samantha Bell, 29, waited months for a heart transplant before one became available.
At one point she said cardiologists told her: "If you don't get a heart you are going to die."
Thankfully the call came and Samantha, from Cambus- lang, underwent a successful heart transplant last year at the Golden Jubilee Hospital in Clydebank.
However, both Samantha and her partner Lee Foley, 30, believe the government should move to an opt-out system to boost the pool of donors.
More than 600 people in Scotland are waiting for a life-saving transplant. Many heart patients die during that wait.
Meanwhile, more than half of the population is not on the register.
Samantha said: "We spoke out about it (opt-out) five or six years ago.
"I don't understand why we have the choice to opt-in. It should be the other way round - it makes so much more sense.
"More people would become donors."
Samantha, a bank worker, developed severe cardiomyopathy when aged 22.
Her condition deteriorated and her heart stopped on a night out.
She had been fitted with a mini defribrillator which shocked her back to life.
Doctors told her she needed to be assessed for a heart transplant.
However, soon after she became gravely ill and was put on a heart pump and onto the "urgent" transplant waiting list.
After three months in hospital she was told a heart had become available and she underwent a transplant in July.
She said: "I know I'll get back to full fitness again and I have my donor to thank for that."
Samantha joined John Forsyth, Scotland's transplant surgery chief and Public Health Minister Michael Matheson to launch the Scottish Government's annual campaign to encourage more Scots to become donors.
Figures show that, as of October 4, more than 40% of the public – 2,116,475 people – are on the register.
Mr Forsyth said an opt-out system could "potentially" reduce the current family refusal rate of 40%.
A debate calling for a change to an opt-out system will take place at the Scottish Parliament on Thursday.
HOW TO HELP
Sign our petition to lend your support to an 'opt-out' system at www.eveningtimes.co.uk You can also sign up on Twitter and Facebook at http://bit.ly/etoptin To join the existing national organ donor register, text 'ETDONATE' to 61611. Texts are charged at the usual standard network rate. You can also join the list by calling the NHS Donor Line on 0300 123 23 23. Calls charged at your contracted rate for local calls.
Register online at www.organdonationscotland.org/nhs_organ_donor_register.html