Asking your spouse "what's wrong?" and "how can I help?" is ineffective. Most likely she'll respond with "nothing", and "nothing".
You just need to implement small lifestyle changes and before she knows it, she's already complied. I find this works best with unmotivated people. They will bend with small changes that are out of their control. For example, if you have a kid who plays too much video games, setting rules or offering incentives isn't going to change his habit. However, taking the gaming console away or don't replace it when it breaks will push him to find another leisure activity. Hopefully you will have books, chess, mind puzzles, etc. laying around the house.
This same concept will work with an unmotivated spouse. If you no longer provide an environment that creates their complacency, then they'll compensate with another behavior.
But alas, the real question is how long can you keep it up since you have to be two steps ahead all the time. It takes energy and creativity.