Editor’s note: Dana Santas, known as the “ Mobility Maker ,” is a certified strength and conditioning specialist and mind-body coach in professional sports, and is the author of the book “Practical Solutions for Back Pain Relief.” CNN  —  If you’ve been hitting the gym regularly and feeling stronger — but also stiffer and more slouched — you may be overlooking key elements that create balance in your workouts. Despite good intentions, many people unknowingly reinforce poor posture with their