Last month I took up Nordic Ski Walking, also called Nordic Walking, and Ski Walking, which is basically walking with poles. It has been great for me, because I was looking for something doable for me at an introductory fitness level, something I could do at varying fitness levels, and something aerobic and anaerobic (so that I wouldn't need to lift weights).
Here are some facts about Nordic Ski Walking (NSW):
1. It burns up to 40% more calories than just plain walking.
2. It is easy and doesn't require skis or snow.
3. It is the fastest growing fitness activity in Europe.
4. It is inexpensive. It costs just the money for your poles, and you're on your way. Mine were $69.95 and involved no gym membership.
I really love NSW, as it involves no gym membership, and allows me to be outdoors. Also, if I feel like an intense workout, I can adjust for it. If I'm exhausted, I can still do it, just slower, and less intensely.
Here is a video of me doing NSW: