This is something which made life easier in the long run, but may not see instant results. When I was growing up we had a period of time where we had to put 25 cents in a jar if we left a room and forgot to turn the light off. For every time the parents caught us turning a light off we would get 5 cents back. It works with smaller amounts as well like 5 or 10 cents if you forget and a penny if you remember. That money usually piled up and went towards things which us kids would use or play with. So, there was a positive reward for forgetting the lights in the end, but it taught us always to think about the light switch before leaving a room. Now it is so second nature that lights get turned out while people are still in the room!