The TRX system (which was developed by a Navy SEAL so that he could train to stay in shape in small spaces with minimal equipment while deployed overseas) leverages gravity and body weight to build strength, endurance and balance while activating the core. Whatever your fitness goals, this workout system can accommodate anyone from senior citizens with injuries to Olympic-level athletes, says Pete Holman, a physical therapist and certified strength and conditioning specialist (CSCS) at TRX. Plus, it’s portable. The trademark black and yellow straps can be used in the gym, at home or even on the road. For best results, use an overhead anchor point that's 7 to 9 feet off the ground and strong enough to support your body weight. Always remember to weight-test your TRX system by pulling hard on it before using it for exercise.