I joined a gym last year and so far, I'm really liking it.
I renewed for this year and got the deal, if I signed up for 3 years, my monthly charge was $20 less! So, that's what I did.
I went crazy there in the months before my March trip. So, going all over the parks was never a problem.
I also signed up for a personal trainer - gotta do something to kick me into gear! - for 4 sessions and I already did 2. That bosu ball thing is hard!
Maybe you can join a local center - like YMCA or a civic center- that has exercize classes vs. joining a gym?
If you have a local University, they also offer recreational activities for a fraction of the price and also free. The one that I work at does. I'm heading out on one of their hikes in a couple of weeks. We did "Robin Hood Forest" a few months back!