Something that is heterotelic has a purpose or motivation outside of itself. If you're working a particular job only for the paycheck, rather than for an intrinsic love of the work, your motivation is heterotelic.
The Greek root hetero means "other," and telic, derived from telos, means "end, goal, or purpose." Literally, then, heterotelic means "other purpose or goal." In psychology and philosophy, it is used to describe behavior that is motivated by an external reward. If you play a sport in high school mainly to earn a college scholarship, your pursuit is heterotelic. The term constrasts with autotelic, which describes something done for its own sake — for example, making art for the sheer joy of doing so.