One way to stay on top of those New Year's resolutions? Tackle two at a time. At these four fitness studios in New York City, your cardio fix comes with a side of sustainability and social consciousness.

Get fit and go green...

The Studio: Green Fitness,

The Workouts: From Bikram to boxing to boot camps, there's a lot to choose from at this boutique gym in Bushwick. Also on offer: Pilates, spinning, yoga, hip-hop, kettle bells, circuit training, TRX, and mixed martial arts.

The Mission: With details ranging from fitness equipment that’s fashioned from recycled metal to reclaimed-rubber floors in the weight room, Green is second only to nature itself in terms of where to score an eco-friendly endorphin rush. You’ll shower under low-flow showerheads, detox in an energy efficient infrared sauna, consume local and organic produce at the juice bar–there’s even a living roof. Click here to check out the full–and long–list of Green’s pioneering eco features.

Eco-friendly Gyms NYC Green Fitness Studio

The Studio: Aqua,

The Workout: A European fitness fad whose rumored adherents include Pippa Middleton and Beyonce, aquacycling or hydrospinning is exactly what it sounds like–a spinning class in a pool, with riders up to their waists in water. It's the water that provides the resistance during this low-impact workout, which is said to be an effective cellulite buster.

The Mission: Regularly home to workshops on clean eating and healthy living, this Tribeca studio is as green as it is gorgeous. Repurposed materials were used throughout the three-story space, where the locker room is appointed with natural bath products and workouts take place in a saltwater pool (requiring fewer chemicals for sanitation than its chlorinated counterparts). When it comes time to change out of that wet bathing suit, don't expect to find any plastic bags here. Members are asked to either bring their own or purchase an eco-friendly and reusable Terra New York tote at the reception desk (which, btw, is made from reclaimed floor boards).

Get fit and give back...

The Studio: The Movement,

The Workouts: Be prepared to sweat hard during this studio's mantra-driven mash-ups of yoga, cardio intervals, dance, core exercises, and strength- and resistance-training. No matter which combo you choose, count on the staff to keep you inspired and motivated.

The Mission: The Movement donates $1 per student per class to the National Brain Tumor Society, the largest nonprofit dedicated to the brain tumor community in the United States.

Charitable NYC Gyms The Movement

The Studio: Studio 360,

The Workouts: Yoga, cycling, or both during the studio’s hourlong Signature Series classes

The Mission: Studio 360 donates $1 per student per class to a different charity each month. For January 2015, that charity is Calvary Hospital. Operated in connection with the Archdiocese of New York, this voluntary, not-for-profit hospital provides palliative care to adult patients in the advanced stages of cancer.