Fitness level is the key to provide accurate and personal feedback based on your heart rate. This is simply because for a fit person the same exercise load (calories per minute) will cause much lower heart rate and training effect than for an unfit person. Therefore, it is highly recommended that you let your PulseOn to estimate your fitness level as soon as possible, and you repeat this every now and then to keep the app – and yourself! – up to date with your fitness level changes.