Jumping jacks are an effective cardio exercise that engages the legs, core, and shoulders while improving endurance. How to Perform: Stand with feet together and arms at your sides. Jump your feet outward while raising arms overhead. Quickly return to the starting position. Variations: š Step Jacks ā Step one foot out at a time for lower impact. š Seal Jacks ā Clap hands in front instead of overhead. š Star Jumps ā Explode into a high jump for increased intensity.