Incongruous means not in harmony or keeping with the surroundings or something that doesn't fit well with other things. In this sentence, the context clue "when she does not follow through with any sports she plays" suggests that the speaker finds it contradictory or out of place that their friend lectures about not giving up but doesn't follow through. The word parts "in-" (not) and "congruous" (harmonious, fitting) also hint at the meaning of "not fitting well" or "not in harmony."
