I don’t even recall where I heard this :).. but it stuck with me for me to write it down
For somebody to do something.. three things much happen at once. The person must want do do it, they must be able to and they must be prompted to do it.
A trigger – the prompt for the action – is effective only when the person is highly motivated, or the task is very easy. If the task is hard, people end up frustrated; if they’re not motivated, they get annoyed.