Totally agree. I picked up climbing several months ago, so I'm still green, but it's a night and day difference from other forms of exercise for me. I've mostly gravitated toward solo sports because I enjoy competing against myself more than competing with others, but running, cycling, weight lifting, etc always felt like a chore and I quickly became bored with the repetition. In addition to being physically dynamic, I've found it works well as a social form of exercise too. There's built in incentives to befriend a wide pool of fellow belayers and we all climb at different levels, so there doesn't seem to be much in the way of interpersonal rivalry, just love of the sport.