I think gardening is one of the most enjoyable exercises. It hurts when you first start planting and weeding on your hands and knees but I notice how much better I feel and how much easier it is to get up and down. Takes about a week to get used to. I know it is not year round but it's fun while it lasts.
I garden a lot and love it. But I don't consider gardening exercise. I definitely use muscles I don't use doing other things, but I don't feel like I've gotten a workout just from gardening.
I am redoing my entire front yard (it looks as if a jungle moved over there). Last night, I worked on it for over 2 hours and I hoped I burned a lot of calories. It was heavy digging and fighting with the roots all the time. I even managed to relocate a ginormous clump of zebra grass and let me tell you, I had to put all my anger into getting it out of it's original spot. I even cracked the handle on my spade and it's the kind of handle that is supposed to never break!