My wife says I don’t challenge her enough. What does this mean and how can I change that habit?

I know, I can’t expect anyone to read her mind, and I know I can ask. You know how it is - if she has to specifically tell me she’s going to notice when I do it.

I love my wife and treat her well. But I know I don’t challenge her much. I’m a peacekeeper and try my best to keep her happy, comfortable, etc. I also know I could challenge her more and offer her more opportunities for that kind of mild interpersonal conflict that keeps a marriage spicy.

But I don’t know how to change the habit without acting differently. Any tips? How does your partner challenge you?