Gym membership or the great outdoors?

My husband and I are trying to get in shape and the town we're moving to has a small gym just a few blocks from our apartment. We're considering getting a membership, my husband is a big fan of treadmills, but hates running outside. I would MUCH rather run outside, but with it not staying light for real long it's hard to find time to do that.   It's $21 a month if we both want to use only the cardio room (or only the weight room) but if we'd like to use both cardio and weight room it's $47 a month. We'll probably get a cardio room membership for a few months to try to lose some weight, unless there's some magical mens fat burner out there, or woman's fat burner? One where no exercise or diet is needed.