Although soft cushions are more inviting, you really want to aim for firm support when shopping for a seat cushion—as long as you understand that firm doesn’t mean hard or uncomfortable but “supportive,” says Preston Brown, DPT, owner of Prestige Therapy and Wellness, LLC. “For prolonged sitting, having firm support is optimal [because it not only] provides more stability, but may help you to unconsciously shift around more, giving your spine the movement that it thrives on,” explains Dr. Brown. Soft surfaces, on the other hand, are more comfortable in the short term but allow our bodies to sink into them, leaving us vulnerable to reduced movement and stiffness.