A non-invasive bodily-attached ambulatory medical monitoring and treatment device comprising: a battery; at least one therapy electrode (114; 114a, 114b) coupled to the battery; a memory storing information indicative of a patient's cardiac activity; a motion sensor configured to detect movement of the patient; a plurality of hardware and software components implementing a plurality of pacing routines, the plurality of pacing routines configured to respond to a plurality of different cardiac arrhythmias; and at least one processor coupled to the memory and the at least one therapy electrode and configured to: identify, within the information, a cardiac arrhythmia from the plurality of different cardiac arrhythmias; and execute at least one pacing routine, from the plurality of pacing routines, corresponding to the identified cardiac arrhythmia to treat the identified cardiac arrhythmia; periodically assess the level of discomfort of the patient by monitoring movement of the patient during execution of the at least one pacing routine with the motion sensor; adjust the characteristics of the pacing routine to lessen the detected level of discomfort of the patient; monitor the cardiac activity of the patient to determine whether the at least one pacing routine resulted in capture, adjust, responsive to whether the at least one pacing routine resulted in capture, the characteristics of pacing pulses applied via the at least one therapy electrode during subsequent executions of the at least one pacing routine such that the pacing pulses can result in capture while minimizing discomfort associated with external pacing by limiting the amount of energy in each pulse to a minimal amount required for capture. a battery; at least one therapy electrode (114; 114a, 114b) coupled to the battery; a memory storing information indicative of a patient's cardiac activity; a motion sensor configured to detect movement of the patient; a plurality of hardware and software components implementing a plurality of pacing routines, the plurality of pacing routines configured to respond to a plurality of different cardiac arrhythmias; and at least one processor coupled to the memory and the at least one therapy electrode and configured to: identify, within the information, a cardiac arrhythmia from the plurality of different cardiac arrhythmias; and execute at least one pacing routine, from the plurality of pacing routines, corresponding to the identified cardiac arrhythmia to treat the identified cardiac arrhythmia; periodically assess the level of discomfort of the patient by monitoring movement of the patient during execution of the at least one pacing routine with the motion sensor; adjust the characteristics of the pacing routine to lessen the detected level of discomfort of the patient; monitor the cardiac activity of the patient to determine whether the at least one pacing routine resulted in capture, adjust, responsive to whether the at least one pacing routine resulted in capture, the characteristics of pacing pulses applied via the at least one therapy electrode during subsequent executions of the at least one pacing routine such that the pacing pulses can result in capture while minimizing discomfort associated with external pacing by limiting the amount of energy in each pulse to a minimal amount required for capture. identify, within the information, a cardiac arrhythmia from the plurality of different cardiac arrhythmias; and execute at least one pacing routine, from the plurality of pacing routines, corresponding to the identified cardiac arrhythmia to treat the identified cardiac arrhythmia; periodically assess the level of discomfort of the patient by monitoring movement of the patient during execution of the at least one pacing routine with the motion sensor; adjust the characteristics of the pacing routine to lessen the detected level of discomfort of the patient; monitor the cardiac activity of the patient to determine whether the at least one pacing routine resulted in capture, adjust, responsive to whether the at least one pacing routine resulted in capture, the characteristics of pacing pulses applied via the at least one therapy electrode during subsequent executions of the at least one pacing routine such that the pacing pulses can result in capture while minimizing discomfort associated with external pacing by limiting the amount of energy in each pulse to a minimal amount required for capture.