Determining a plurality of heart rate sections for an individual, and selecting a plurality of songs, wherein each of the plurality of songs has an average beats per minute approximately equal to an average beats per minute of one of the plurality of heart rate sections, and playing the plurality of songs in a sequence on a song playing device. The plurality of songs includes a middle song, which has an average beats per minute which is greater than the average beats per minute of all of the other songs of the plurality of songs. The plurality of songs includes one or more preceding songs which precede the middle song, and each of which has an average beats per minute which is less than the average beats per minute of the middle song. The plurality of songs includes one or more succeeding songs which succeed the middle song, and each of which has an average beats per minute which is less than the average beats per minute of the middle song.