HOW: Get a band or cable anchored somewhere between waist and shoulder height. While standing perpendicular to the anchor and holding the handle with both hands close to your chest, step out to build tension in the band. Once there is enough tension, press your arms forward away from your chest until your elbows are fully straight. Hold that position for a moment while keeping your hips and shoulders square facing forward, then bring your arms in, step back in, and repeat.
FEEL: You should feel your core and back muscles working as well as your arm muscles to maintain optimal position and form. You may also feel your hip and thigh muscles working as well to maintain position.
COMPENSATION: You should step away from the anchor until there is enough resistance that is challenging, but not too hard where you can't maintain optimal form. Do not let the band rotate your upper body, keep your arms straight and hips facing forward. Try to avoid twisting your back.