Don't worry about lasting change, worry about what your contribution to the problem is. I think the veg*n community is a good example where a proportionately small group of people stuck to personal commitments to not eat meat or animal products, and have (decades later) gotten mainstream acceptance for that. You can now have a vegan meal at Burger King, but only because a group of people weren't worried about making lasting change they were just worried about living in line with their values :)