A method of operating a first apparatus 100 in a wireless communication system is proposed. The method may comprise: determining a time duration in which a first active time and a second active time overlap; performing SL transmission or SL reception of a service related to a smaller priority value among a first priority value and a second priority value, within the overlapping time duration; and performing SL transmission or SL reception of a service related to a greater priority value among the first priority value and the second priority value, outside the overlapping time duration.