No matter if you are public relations practitioner, geophysicist, or dentist, sales is part of your day, every day. Unless you have everyone you know do whatever you ask without question (and if you do, I'm jealous), you have to sell our thoughts to other people.
Sales is pretty simple (not easy, simple). Just ask a lot of questions, listen and ask more questions. No one is truly satisfied with the status quo so you will eventually ask the question that will uncover a hole that you can fill.