Configurations of an activity assistant processing system are disclosed that provides users with dynamically-selected activities that are intelligently tailored to a user. The subject technology accesses an index of activities. A score is then determined for each particular activity in the index of activities. The score is based on plurality of signals associated with user-specific parameters and global parameters to determine the quantitative importance of a particular activity. The subject technology identifies a subset of activities within the index of activities using the activity assistant processing system in which the subset includes at least one activity with a corresponding score that is greater than or equal to a decision threshold for the at least one activity. At least a portion of the subset of activities is then ranked based on the quantitative importance of the particular activity using the activity assistant processing system.