My therapist is fond of a similar exercise and I've learned to adopt it.

While it may seem a waste of time, visualizing an emotion, giving it a colour, consistency, texture, material lets you be an observer to it. By forcing yourself to study it, you need to step outside of its bounds, separating the you from the emotion itself. That distance you have created and held for a few moments is a welcome relief and often makes it apparent that you are a separate entity from your pain. The further away you are from it, the less painful it is. And the more you look at it, the weaker it seems. At the end of the exercise you are more aware that whatever tormenting you was just a fleeting moment with little power over you.

I find it is a brilliant and incredibly powerful concept to internalise. You can find this is the exact idea expressed in stuff like Dune's Litany Against Fear (by reciting it, you are visualizing your fear as a third party, outside of you), or meditation (remaining a passive observer to your thoughts)