That's not quite it. La décroissance is inspired by the idea of actually going against what all modern political and economical strategies are focused on: growth. But your own personal lifestyle does not have to change drastically to go along degrowth, and can keep on evolving in a 21st century mindset (ie aspiring to new technology etc).

Our current approach to consumption and ressources is required to change, but not as in "revert back to the stone age", but more or less along the lines of localized food management (do not buy stuff grown half-way across the world and brought in by plane), a lot more recycling and renewable energies (oil dependency is one thing that must be totally broken), company profit distributed to company employees and not share-holders etc etc. Basically your average, expected, left-wing and green party positions ... but the actual degrowth bit is what makes the difference ... that is basically: "implement and follow a plan for negative growth in rich countries, so that the rest of the world can catch up and we can all then stabilize ourselves at a stable level of consumption we're all comfortable with and that is compatible with the ressources of this planet (instead of all competing and going for more growth more growth more growth and wrecking everything on Earth)".