Answer:
1. You will be a able to sleep at night, if you have a conscience.
You will meet many like minded people if you believe in what you are participating in.
2. If the campaign or movement actually causes change, you will probably get at least a small sense of accomplishment.
By participating you might pay attention to politics more in general afterwards, and policy does affect all of us.
3. Some people will respect you more, since they know you will stand up for your beliefs.
This is a little more light hearted, but if you participate in any protests, you might get some cool scars.
