Not to sound preachy, but just do your running/walking/jogging/biking outside. It's far superior as you're breathing fresh air and getting Vitamin D via the sun. For weight resistance...if you don't have the room, then yeah, a membership to a gym makes sense.. Just make sure it has a pool as not only is swimming cardio AND weight resistance training, it helps hone a skill that could save your life (or save someone else's). I don't get it when people run inside in the spring, summer , fall or winter (in areas without ice/snow). I probably never will.