In mathematical modelling tasks, there is always a real-world context that is crucial to solve the task. While it is already known that interest in mathematics has an influence on the performance in mathematics, it is an open question, whether this applies also to personal interest in the context of a modelling task. This research project therefore investigates what influence the personal interest in the real-world context of a task has on its modelling process. The focus of this chapter lies on the modelling sub-step validating. To investigate this the work processes of ten 7th graders on two modelling tasks (one with much, one with little personal interest in the real-world context) are compared using a qualitative content analysis with the modelling steps as categories. The comparison of the two tasks shows that personal interest in a context can have a supportive effect on the occurrence of validation sequences.