first night they have the ability to go home the next day.
2. try to make it as comfortable as possible (within reason). offer them any of your gear that will help with the experience. your friend will not want to go out and buy a ton of camping equipment if they think they will not enjoy it to begin with.
4. before the trip, meet with your friend. come up with a menu of the meals and who will do what. again, any bit of “ownership” may persuade your friends that camping is a great time!
5. if they are still resistant to come along – invite them for just the evening 