We can’t twist people’s arms to become minimalists, but we can help them make minimalist-friendly choices. Here’s some examples:
Offer to carpool. It saves gas, it’s green, and it’s a chance to build a friendship (and possibly have some minimalist influence)
Recycle your stuff. Give your stuff to friends who are looking to get what you have. You become more minimal while helping them keep from buying.
Host events. Big events like a BBQ or small things like taking a hike. After all, the purpose of minimalism is to enjoy life, so let others get a taste of that.