My mum was a wonderful mother. She died, aged 80, of Alzheimer's disease, which was dreadful to watch. I remember she said to me: 'Believe in yourself because no one else is going to do it for you.' I'm sure a lot of my success is due to her words of advice.

This quote means that the speaker’s mother, who was a great parent to them, said to them that they must have faith in themselves and their abilities because nobody else can do it for them. The speaker believes that their success was partly their mother’s words of wisdom to them. The speaker’s mother sadly died at 80 years old from Alzheimer’s, which was very heartbreaking for the speaker to endure.