Answer:
Hart experience what is called Flow or has a Flow experience
Step-by-step explanation:
Flow experience describes the mental state of mind which an individual achieves by performing an activity or working in such a way that he or she is fully focused on the job/activity, enjoys the process and loses track of how time flies.
In other words, Flow describes happiness, energized focus and no awareness of how much time flies when engaged in an activity that one loves and is quite skilled at. It can now be understood that Hart loves volunteering with Humanity and experiences flow while he is at it.