User interface design and feedback are important in personalised behavior change support systems. This paper discusses two service platforms that monitor user’s physical activity through wearable sensors and that present the user personalised feedback. Important principles for effectiveness of such systems are personalisation or tailoring, context- awareness, feedback and interaction. We focus here on the presentation of feedback to the user. We present results of a number of short and long term user studies in which we compare different forms of feedback presentation: text, graphics and with or without an anthropomorphic graphical talking character. Results show that although some users like the talking character they don’t have a positive effect on adherence to the activity program. The outcomes of the user evaluations support our beliefs that personal motivation is of primary importance for the effectiveness of these systems. Technical challenges ahead are to support more personal and context-aware feedback, more variations as well as the possibility for more interaction with the coaching system.