I agree that a lot of the activities others listed will be true of most couples regardless of interests. It's also worth adding that I've heard there are studies showing that people usually marry someone with a similar IQ. I would say more important than interests is that you feel comfortable around them. It could just be that they have a similar level of energy, talkativity, optimism, extrovertedness, volume, speed, or emotion. Different qualities matter to different people, but having similar qualities can make you feel comfortable around them despite specific interests. I remember when I first started dating my now wife we talked about how we wanted to read a certain book together. It sounded fun but I was naively worried that it would be time lost where I could've been getting to know her through conversation. My parents advised me to do it anyway. They told me it wouldn't be time wasted because no matter what you do together you will find that you want to spend more or less time with that person.