Questions: Travel

I will soon be taking over the organizing and managing of a fundraiser's booth of my local cat shelter. So basically, I need to seek and manage volunteers who will be manning the booth (which will be set up at a farmer's market).

Now the issues that the previous coordinator have told me are that it's always hot outside, so people tend to not want to do it. Among these options, which do you think are good ideas in order to (a) get more volunteers, and (b) get more repeat volunteers, and (c) get the volunteers more motivated to raise more money (this is less important than a and b).

Feel free to add your ideas! What would make you want to spend a few hours on your weekend to sit/stand outside in 30+ degrees celsius (in the shade) to raise money for cute kittens? Tell me your experiences in volunteering if you've done it before! Thanks in advance!