We do not deliberately change anything when we are uplifted. We use the mind to generate a better function. If, in the moment, you can generate a smiling thought instead of a crying thought, you are actively uplifting yourself. So, each moment is one of liberation in which you are set free. You are simply using the mind's creative ability to generate a positive expression. Your body is  elevated, and you experience fewer wandering thoughts. This is the essence of change. When your mind is uplifted, so is your body. You are no longer the person you were the day before, or even the moment before. The past is past. What happens in any one moment is as impermanent as a spring snowfall. ¶ by Zen Master Miao Tsan