The human mind responds to stimuli - it is for that reason that zombies aren't possible because zombies don't respond highly to stimuli - however that is how the human mind functions, by responding, recognizing and adapting to stimuli.
Stimuli from thoughts, emotions and the environment all help keep the mind active and alive. That doesn't necessarily mean that a person needs strong motivations all of the time, however. In order for the brain to function a complex set of inter-actions needs to be occurring. Emotions, thoughts and stimuli must be continuously triggering complex feelings that form a sort of 'feeling base' for the unconscious.
That is different from Damasio's 'background feelings' which could be viewed as just being simple feelings. The feeling the unconscious mind generates is complex and constantly dependent on stimuli and also (necessarily) constantly feeds the mind with its own stimuli.