This is a term we are all familiar with, however in the words of David MacKay: If everyone does a little, we’ll achieve only a little”.
There is also a danger that if people are only asked to do one small thing, they might feel virtuous about it and stop there. Even worse, they might think that because of all good work they are doing with reusing their plastic bags, they are worth a trip to Thailand! This is also known as the rebound effect.
It is good to praise people for the small step they have taken. If someone has never carried out a low carbon action before, a small act such as switching off lights when leaving a room might be a significant action to him or her personally. However, you need to frame it as the first small steps at the beginning of a long journey.