Despite the growth of personal digital information use, both in scale and application diversity, conventional user models are still reliant on limited user input data to improve a variety of services for specific applications and tasks. This trend toward increased application diversity renders it difficult for a system to generate inferences about a user's evolving interests and naturalistic tasks in real-life settings. This workshop paper introduces a novel approach, aimed at training a user model to recognize real-life tasks on the basis of naturalistic user behavioral data via continuous screen monitoring. The resulting task model could be used in real-life settings for personal information assistance, which proactively retrieves useful documents and resources for the user, on a personal computer, with respect to the task context and information demand.