Sunbury residents are being encouraged to ask themselves this question and make positive changes to their lives.

Pastor James Natsis, of the Sunbury Baptist Church, is running a six-week challenge to encourage people of all denominations to find what is important in their lives.

"The campaign is basically geared at helping people to consider how they would act differently if they had only a month to live; how they could live a life without regrets, how to build deeper relationships and leave a lasting legacy."

Mr Natsis started the campaign - which is based on a book, One Month to Live, written by an American couple - because of many cases of depression amidst struggling families in the area.

"Some questions many people have are 'what am I here for?' and 'what is my purpose in life?'. The challenge can address this."

About 80 people from Sunbury and the Macedon Ranges have already taken up the challenge. Participants meet each week and discuss the changes they have made and the difference it will make.

Mt Macedon resident John Muys, 67, is already seeing the changes in his life. "I've come to answer basic questions like who I am, what my identity is, why I am here and is there a purpose?

Mr Muys says if he had only one month to live, his priority would be spending time with his family, including his wife and children. "When I have my last 60 minutes I'd like to reflect back on relationships and things in my heart. I think I get very busy ... you go with the flow, then life passes you by. It's a good opportunity to take stock and think through what's important.

"On reflection I've come to realise that it's so easy to fill my life with things and put relationships on the back burner when in actual fact when you realise life's brevity, whether one month or more, we only have a certain amount of time. I encourage anybody out there to go through this exercise and use the 'one month to live' challenge as a catalyst to think through priorities and think about what is important, rather than live a life with regret."

To get involved, contact the Sunbury Baptist Church on 97407683.

Nicole Highet, deputy CEO of depression initiative beyondblue, said while the campaign was not a cure for, or prevention of, depression, a positive attitude could go a long way.

"People who are going to be happiest are those who are considered optimists. They look on the bright side, but it's based on reality," she said.