Not only can intrinsic motivation be used in a personal setting, but it can also be implemented and utilized in a social environment. Instead of attaining mature desires, such as those presented above via the internet which can be attained on one's own, intrinsic motivation can be used to assist extrinsic motivation to attain a goal. For example, Eli, a 4-year-old with autism, wants to achieve the goal of playing with a toy train. To get the toy, he must first communicate to his therapist that he wants it. His desire to play is strong enough to be considered intrinsic motivation because it is a natural feeling, and his desire to communicate with his therapist to get the train can be considered extrinsic motivation because the outside object is a reward (see incentive theory). Communicating with the therapist is the first, the slightly more challenging goal that stands in the way of achieving his larger goal of playing with the train. Achieving these goals in attainable pieces is also known as the goal-setting theory. The three elements of goal-setting (STD) are Specific, Time-bound, and Difficult. Specifically, goals should be set in the 90th percentile of difficulty.