Some one told me once that stress can be related to the water in a bottle as you hold it at chest level. There may not be much of it in there at the beginning. Your "water" can be something like a simple stress... What am I going to eat for dinner? What am I going to wear to work today? These are easily dealt with, and sip- away goes some of the weight.
But what do we hold onto? Ending of relationships with friends or lovers, loss of your job... Those things that we hold close to our heart and let it fester. And so you are left holding this heavier and heavier thing at chest level. One minute, Easy. Two minutes, Easy. Longer... Hours, days.