There have always been people who loved sports in Primary school, they continued to love it in High school, then University and so on and so on.
And then there are those people who had never enjoyed it. Just they were not good enough or they didn't felt any enjoyment. And when all the schools and universities are over, they mostly get in a bit lazy lifestyle - partly because of sedentary job, but they are not even trying (or not trying hard enough) to get their lifes active - It's not for me, I don't like it, I have something better to do!
Been there done that! I honestly hated sports at school, I did hate it a little less at university, but I started to enjoy exercises and understood that this "has to be" a part of my life a little later - when I found a good way for me to be introduced to physical activity! So I just had bad experience back in they days. That doesn't mean that I'm a lost cause :D
So I don't believe that people hate sport/activity, they just haven't found their own style jet!
Our ancestor where running around trying to survive and find food- you can easily get out of this - we don't have to do that anymore,
I suggest to keep in mind that we have muscles and their function is to move our body.
I'm not saying that you have to spend half of your life at the gym - brisk walk, dance, cycle, workout at home, play with kids etc. will do it - every day for at least 30 min.
And then you do some more serious workouts (again not nececerally at the gym) 2-3 times a week.
You don't have to allways love it, but your body and mind needs it!