## 1 Introduction  
In the contemporary age of continuous technological evolution and innovation, smart interface technology has made notable strides, fundamentally reshaping the interaction between humans and computers. Among these advancements, virtual reality (VR) technology has rapidly developed and is gradually being used more extensively due to its affordability and miniaturization. VR constructs three-dimensional (3D) virtual environments through computer simulation, offering users multiple sensory simulations that mimic real-world settings and objects in 3D space in real time [1, 2]. With advancements in computing performance, VR has been applied across various industries and contexts, including gaming, healthcare, training, and design [3, 4]. This study specifically investigated the potential of VR to motivate physical stretching and promote physical activity among users. In common application scenarios, differences can be observed between two types of goal-related interactions: \"exploration and browsing\" and \"goal-directed guidance\". A previous study concluded that applications often integrate elements of both interaction types [5]. For example, travel applications cater to diverse user preferences, with some allowing users to casually explore and browse destinations and others providing structured guidance for users following a step-by-step approach to achieve their travel goals. Expanding on previous research, this study investigated the \"exploration and browsing\" type of interaction, which closely resembles the preliminary phase of exploration. VR interfaces provide users the freedom to navigate without specific predefined task objectives and do not urge users to complete tasks within strict timeframes. This allows users the opportunity to casually peruse and search for task objectives in a more relaxed interaction pattern. In this study, participants were provided a VR creation tool, namely Gravity Sketch, to facilitate autonomous exploration and foster creative expression, enabling them to freely manifest their imaginative ideas. Figure 1 illustrates the diverse, spontaneous, and unrestricted nature of user goals in this context. The second interaction type is termed \"goal-directed guidance\", which entails establishing distinct and explicit task objectives for users to accomplish methodically. In this study, a virtual dumbbell exercise game was employed to guide users to complete predetermined postures within a limited timeframe and reach various \"achievement points\" through a series of various arm movements. To continually motivate users to engage in appropriate stretching activities, the users were incentivized with visual and auditory rewards upon successful task completion. Figure 2 depicts the users' objectives as specific, unambiguous, and singular in nature. Despite the allure and entertainment value associated with VR, whether VR motivates users to engage in stretching exercises and achieve enhanced physical activity outcomes remains unclear. Moreover, whether the inherent differences between exploration and browsing and goal-directed guidance lead to variations in usability, emotional responses, flow experience, and technology acceptance requires further investigation. Insights from a comparison of these differences between interface types could help in proposing valuable design recommendations for promoting sustained and effective physical activities. This study investigated the characteristic differences between the two primary interface interaction styles in a VR application environment, namely exploration and browsing and goal-directed guidance. Specifically, we compared various indicators and activity effectiveness and analyzed the results, which facilitated the identification of advantages  
Figure 1: Exploration and browsing (e.g., Gravity Sketch program, a freeform creativity VR tool). Figure 2: Goal-directed instruction (e.g., VR exercise application developed in the present study by using Unity). and the proposal of design recommendations.