How about persuading people to take up cooking meals at home more and eating out less? Possible points you could research and base your persuasion on are (but not limited to):
1. More control over nutritional and caloric content
2. Ecological benefits (no paper cups or styrofoam burger boxes)
3. Economic benefits from buying ingredients, instead of processed foods
4. Psychological benefits from taking an hour out of the day to sit down as a family and have dinner
Why people should get more involved with politics, governmental issues, etc. so they can participate in the present and future of the country and that even one person can make a difference, etc.
Or you could talk about the environment and what people can do to make the world a better place and that they can make a difference, etc.
Anything as long as you get them involved, has to be something interesting, real, informative, etc.
I think the best 'persuasive' speeches are ones that you have a very strong opinion about. If you are just getting up there and talking about a random topic, it is hard to get peopel's attention. If you have first hand experience, people will listen because they like it, or it will bother them as they think you're wrong.
puppy mills
adopting a dog from a dog pound instead of a puppy from a store
neutering and spaying your pets
the over populated cat and dog world due to selfish people trying to over breed dogs that half end up in shelters
Bush was right all along. There were weapons of mass destruction all along in IRAQ...he was right on he money.....they were just either hidden underground or move to Syria. Saddam had well over a year to move and hide everything after 9/11.
A co-worker said steer away from politics and religion because that is something people feel so strong about. They may just end up not listening because they may disagree with your viewpoints. He got an A for his speech trying to persuade people into believing ghosts exist.