the destination has a good enough payoff to make the discomfort of backpacking worth it, (3) that the natural conditions are good (e.g. good weather, not many insects), and (4) that sleeping comfort is maximized.
When I took my wife on her first backpacking trip, my pack was 50+ lbs because I wanted to make sure hers was super light and that I was carrying all the comforts I could. She had never really done anything outdoorsy before that, but now she is one of those people who watches survival shows like Naked and Afraid and thinks it looks fun.
First impressions make all the difference.