constant interaction constant internal constant interruptions constant investment constant irritation constant issue constant learning constant length constant level constant light constant load constant loop constant love constant low constant magnetic constant maintenance constant mass constant may constant medical constant member constant mental constant monitoring constant motion constant movement constant nagging constant need constant negative constant noise constant number constant observation constant of integration constant of proportionality constant operation constant or variable constant output constant over time constant pain constant part constant performance constant ph constant phase constant physical constant pitch constant police constant position constant positive constant potential constant power constant practice constant prayer constant presence constant pressure constant price constant prices constant problem constant process constant product constant production constant progress constant proportion constant pursuit constant quality constant quest constant questioning constant radius constant rain constant rate constant ratio constant reassurance constant reference constant refrain constant region constant regions constant reminder constant reminders constant renewal constant repetition constant research constant resistance constant review constant ringing constant risk constant rotation constant scope constant search constant section constant sense constant size constant sorrow constant source constant source of inspiration constant speed constant state constant state of change constant state of fear constant state of flux constant stimulation constant stirring constant strain