Work with mission-driven businesses. B Corps[0] are a good place to start. There's nothing quite like coming to work every day with a group of like-minded folks who want to make a dent in the universe.
My company, www.grove.co, strives to help families making it easy to buy sustainable products vs. conventional CPG. It seemed a bit crazy when we started, but now literally thousands of families get sustainable products from us every single day. It's hard to make a big impact on your own, but organizations and companies can do great things.