We've all heard the expression "No pain, no gain." But oh how wrong that saying is when it comes to working out. A recent article in the Wall Street Journal recently talked about exactly how and why rest is so essential to any one who exercises regularly--and especially for those who train for endurance events like triathlons and marathons. Bottom line, always listen to your body, cross train regularly, and when your trainer says slow down, do it! It's for your own good.