A motivational poster placed at a choice point between escalator and stair use, in a city centre underground station, doubled stair use. The study also showed that men and boys used the stairs more than women and girls both before and after the poster intervention, but there was no obvious explanation of this finding. Follow up interviews with 200 stair users or escalator users showed that motivational posters can change the behaviour of people who are not very active as not all those using the stairs were regularly active. The barriers to stair use were time, laziness, and effort, while the motivations for stair use were saving time and improving health. Women cited laziness as the key barrier to stair climbing and in comparison with men perceived stair climbing as requiring more effort.