I know you mentioned outdoor workouts, but I would strongly recommend yoga if you want a full body workout -- strength, flexibility, gets your heart rate up too if you choose a class with a flow, like vineyasa or ashtanga. Also -- aerobics and spinning classes are great for building your core muscles, and you have some motivation in the other people who attend class.

Also -- are you into hiking? Fall is such a great time to get into the mountains and explore. Plus it's a great workout.