I've not used a gym in many years, but I reckon I get enough exercise anyway. I don't have any real aims apart from running better, but I would like to be in reasonable shape generally. There is a gym fairly near, but I don't want to spend too much more time exercising so I'll save my money. One of my kids is a personal trainer and so they could give me tips if I asked.
I get that other people want a specific place to go for exercise as it helps them focus on that and there may not be good places to run. I would think there can be a social side to it too. I've not been too much into team sports since I played Ultimate at university and I was not great at it.
RE: You don't need a gym membership to get in shape