The simple message that sustainability and clean energy are positive, evolutionary steps that offer a more intelligent, creative way of living might motivate people more than "you have to change or you and your children and grandchildren will die!"
there's a big truth there. And the positives about reducing consumption need to be put front and centre. They are, as you say, far more persuasive than fear and guilt.
The fact that, above a certain level of wealth, more money does not make people more happy, in fact there is a correlation with increased wealth and increased mental health problems.
also, relocalisation is beneficial to us all. Safer communities, less commuting.
Cutting energy consumption means cutting energy bills too.
However, there are some things that we cannot get around. If you want to have a sustainable level of carbon emissions, it means no aviation. It means seasonal food crops and goodbye to lots of the stuff that we enjoy eating year-round.
Even if we get beyond our culture's deeply held belief that consumption is a mark of virtue and success, the fact is that we all love access to mangoes and strawberries in winter, we all love tropical beaches. There is no honest and positive way to sell that one to folks as far as I can see.