How to fundraise for a good cause?

I am fundraising for a cancer walk. I have asked people to donate, but no one seems to be responding. What else can I do to make money for donations? If I don't meet the minimum requirement, I will end up having to pay all of the money. People say they will donate and then don't follow up, and I don't want to har them... Does anyone have any good fundraising ideas besides simply asking for donations?