Now can you imagine gasping for every breath - having to use oxygen 24 hours a day and not knowing whether you're going to live or die. Well that's the terrible situation 27 year old Sam Yates from Basingstoke is in.
She suffers from cystic fibrosis - and desperatley needs a double lung transplant - but after years of waiting a match has never been found.
At the moment she's in hospital - suffering from a severe chest infection - but the future is looking bleak.
In our special series - From the Heart - our Correspondent Stacey Poole has been to meet her - and find out what life is really like on the Transplant list.