Fitness Friday: Make it Fun

If you discount my pathetic senior year of cross country, I participated in my first ever 5K last weekend, but at a walking pace..and with my dog. My dog James is in his absolute happy place when he's surrounded by other dogs and people and I couldn't deny him of that and the exercise that comes along with it. So we joined up with our friends Katherine and Steve. They brought their lab Charlie and then James and Charlie were instant pals (at least in James' warped mind.)
I was especially happy to participate to help the local humane society and get some extra exercise in. Forms of exercise disguised as a good time like this 5K are things I'd like to participate in more often. In the past, I've avoided nature at all costs and now I'd like to do more horseback/trail riding with my mom and maybe even try hiking. What types of exercise/fun are your favorite? I need more ideas!