Abstract: Among other things, a computer-implemented method includes, on successive occasions over a period of time, gathering measured data and self-reported data that represent health states of participants in a health goal system, based on at least some of the gathered data, determining, by machine learning, data representing a relationship between sequences of self-applied interventions and health states of participants who belong to respective groups that share similar characteristics, calculating scores representing characteristics of interactions between participants and the health goal system, and based on the scores and the data determined by machine learning, choosing elements of conversations to be provided to the participants, elements of the conversations being chosen to affect (i) behaviors, (ii) health states, or (iii) health awareness, or a combination of any two or more of them, of the participants, the elements of the conversations comprising questions posed to the participants on user interfaces of e

Abstract: Among other things, a method includes, on successive occasions over a period of time, gathering measured data and self-reported data that represent a health state of a particular participant in a health goal system, using the gathered data in a machine learning engine to select, for a current occasion, a current intervention to be self-applied by the particular participant, the machine learning engine having learned from data gathered from a group of participants on successive occasions, the effectiveness of sequences of self-applied interventions in improving the health states of participants who belong to respective groups that share similar characteristics, the current intervention being expected to affect, for the particular participant (i) a behavior, (ii) the health state, or (iii) a health awareness, and providing the particular participant, electronically through a user interface, information that will encourage the particular participant to engage in the selected self-applied current intervention.