Steven used to spend only 1 hour in the gym 3 times a week, but recently he has been spending 3 hours a day 7 days a week working out. He has noticed that his back is chronically in pain. Even so, as soon as Steven stops a workout, he starts thinking about what he did not accomplish. This is an example of what type of behavior?
A.
habit building
B.
addictive.
C.
impulsive control.
D.
tolerant.