The achievement of self-actualization was first discussed by Abraham Maslow as part of his hierarchy of needs, and it represents the completition of the highest level of the hierarchy and the emergence of the "fully functional person". Self-actualization is basically the achievement of meaning in one's own life.
The 20 minute physical activity I performed was doing yardwork. It was fairly easy to do, besides a lot of bending down involved to pick up sticks. I did it in my front and backyard for a bit over 20 minutes, and no one did it with me.