A system for monitoring the health of a person, the system comprising - at least one sensor (4A, 4B) capable of measuring at least one physiological signal generated by the autonomic nervous system of the person for providing measurement data, - data processing system (5A, 5B) configured to ∘ store a reference indicator, ∘ store a health-monitoring session plan, ∘ receive measurement data from the sensor (4A, 4B) during a plurality of consecutive health-maintenance sessions (10A...N, 10A'...N') in order to collect a plurality of measurement data sets corresponding to said health-maintenance sessions (10A...N, 10A'...N'), ∘ determine at least one health indicator based on the measurement data sets, said at least one health indicator being sensitive to physiological state of or changes in the autonomic nervous system, ∘ compare the at least one health indicator with said reference indicator, and ∘ change the stored health-monitoring session plan based on the comparison of the health indicator with said reference indicator, wherein - the at least one health indicator comprises a plurality of second health indicators separately determined based on each measurement data set and representing temporal variation of measurement data within said measurement data sets, and wherein - the at least one sensor (4A, 4B) comprises a heart rate sensor, the at least one physiological signal comprises a heart rate signal, and the at least one health indicator comprises a heart rate variability index, or wherein - the at least one sensor (4A, 4B) comprises an electroencephalographic sensor, the at least one physiological signal comprises an EEG signal, and the at least one health indicator comprises a brain activity index, wherein the data processing system (5A, 5B) is configured to calculate the second health indicators based on ∘ first measurement data contained in the first half of a measurement data set, corresponding to the first half of a single health-maintenance session (10A...N, 10A'...N'), and ∘ second measurement data contained in the second half of a measurement data set, corresponding to the second half of the single health-maintenance session (10A...N, 10A'...N'), wherein the single health-maintenance session is a single meditation session, a single exercise session, or a single controlled breathing session. - at least one sensor (4A, 4B) capable of measuring at least one physiological signal generated by the autonomic nervous system of the person for providing measurement data, - data processing system (5A, 5B) configured to ∘ store a reference indicator, ∘ store a health-monitoring session plan, ∘ receive measurement data from the sensor (4A, 4B) during a plurality of consecutive health-maintenance sessions (10A...N, 10A'...N') in order to collect a plurality of measurement data sets corresponding to said health-maintenance sessions (10A...N, 10A'...N'), ∘ determine at least one health indicator based on the measurement data sets, said at least one health indicator being sensitive to physiological state of or changes in the autonomic nervous system, ∘ compare the at least one health indicator with said reference indicator, and ∘ change the stored health-monitoring session plan based on the comparison of the health indicator with said reference indicator, wherein ∘ store a reference indicator, ∘ store a health-monitoring session plan, ∘ receive measurement data from the sensor (4A, 4B) during a plurality of consecutive health-maintenance sessions (10A...N, 10A'...N') in order to collect a plurality of measurement data sets corresponding to said health-maintenance sessions (10A...N, 10A'...N'), ∘ determine at least one health indicator based on the measurement data sets, said at least one health indicator being sensitive to physiological state of or changes in the autonomic nervous system, ∘ compare the at least one health indicator with said reference indicator, and ∘ change the stored health-monitoring session plan based on the comparison of the health indicator with said reference indicator, - the at least one health indicator comprises a plurality of second health indicators separately determined based on each measurement data set and representing temporal variation of measurement data within said measurement data sets, and - the at least one sensor (4A, 4B) comprises a heart rate sensor, the at least one physiological signal comprises a heart rate signal, and the at least one health indicator comprises a heart rate variability index, or wherein - the at least one sensor (4A, 4B) comprises an electroencephalographic sensor, the at least one physiological signal comprises an EEG signal, and the at least one health indicator comprises a brain activity index, ∘ first measurement data contained in the first half of a measurement data set, corresponding to the first half of a single health-maintenance session (10A...N, 10A'...N'), and ∘ second measurement data contained in the second half of a measurement data set, corresponding to the second half of the single health-maintenance session (10A...N, 10A'...N'),