For Kirstine Knox, chief executive of the Motor Neurone Disease Association, the battle with HIV in the late 1980s was a pivotal time.
After leaving the University of Glasgow in 1987 with a degree in immunology, she moved to London to work on trials of the first anti-retroviral treatments for HIV, designed to inhibit the spread of the virus in the body.
"It was a frightening disease," she recalls. "People were dying very quickly and it was a huge societal issue. The role was very much about moving the work done in labs into the clinics. It was extraordinary to see the change these treatments brought about."
Knox would spend the next 18 years working as a scientist, with roles ranging from cancer research at Oxford University to a stint at the Department of Health helping establish the National Patient Safety Agency.
But in July 2005, she moved into the charity world as chief executive of the MND Association. "I already knew about motor neurone disease -it's a devastating and fast-moving disease," she says. "Most people who get it die within a couple of years. So there's a real need for an organisation to support them and their families, and to push the importance of research."
Life in the third sector, she says, is very different from her previous job in the civil service. "It's remarkably devoid of politics," she says. "There's a focus on what needs to be achieved, not personal agendas. For the first six months my main thought was 'everyone's so nice'. "
But this niceness can, she admits, sometimes mean that charities avoid making the management decisions they need to make. "The caring culture can lead to a tolerance of underperformance," she says. "We're trying to bring management best practice into the caring culture."
As a result, it has set up a performance management system that outlines what is expected of staff and how to deal with underperforming employees.
Knox's time working with some of the world's leading scientists has also made her ambitious for the charity. "When you are a charity it's easy to end up always thinking about funding, so you can lose sight of the big picture," she says. "I've worked with a lot of people who have had big visions about what they wanted to achieve and I hope to bring this into the MND Association."
The charity has doubled its income in her four years in charge, and so the signs are that this culture of ambition is starting to be realised.