Also, body and soul is so intertwined. If you feel happy/sad/angry, you don't only think about it, you feel it in different parts of your body. If something makes you smile, you might feel a warmth spreading from the core, or if you are angry you might become very tense. Emotions tend to gather at certain parts, like the hips. By stretching and releasing those tensions a flood of emotions might come along with them. At least that happens to me sometimes.
Anyways, the course had nothing to do with what I just wrote. Most of it was old news (went to the same course last year) but we also got some new valuable input on evaluating yourself. It doesn't have to be related to work out - it can be used for any area in life. Instead of thinking about what you do wrong, you should think in the terms of how can I improve this? Then you should look forward to next time when you can try it again - instead of feeling let down that you weren't good enough. This way of thinking creates a positive spiral!
To sum up, take care of your body it is the only one you have. Even though you don't always succeed in your work out/meal plan or what ever it might be, think in a positive way of what improvements you can make rather than racking down on yourself. (yes it is easier said than done, but at least by thinking about it we are one step on the way)