According to the passage, the key to motivation is A. setting challenging goals. B. not letting our fears pull us back. C. changing our goals periodically.

Explanation

As author outlines in the passage, the key staying motivated is setting challenging goals which make you get out of the comfort zone. Also, the passage does outline the need to not letting fear demotivate us in our quest for achieving the set goal. Both the statement A and B are correct in the context of passage. Option A is correct.