Actually, … are you sure?
Nitpicker here but I would suggest it is exactly the other way around the relationship between acceptance and contentment. Being content you are not motivated for action anymore. Contentment is when you have found your place or the state that comforts you and you are almost happy, mildly achieved happiness.
Contentment exactly does settle. That’s what it means to be content. to chill in a bliss, a state that springs from the depths of gratitude.
Acceptance on the other hand is the motivator. Lost a limb? Accept it and learn to use the other better. Alone and poor? Accept it so you’ll have the time to pull yourself out. In theory. I haven’t lost a limb, neither am I alone or poor, just illustrating a point. The point that acceptance frees time for action, instead of being angry about a situation, instead of fighting the reality which you live, you accept things and work your way up from there on.
Acceptance is a form of letting go of attitudes, ideas, past and so on. Acceptance doesn’t settle but instead it helps one reinterpret their experiences.
Contentment is a desirable state that fills time. In a content state you are not driven to change anything because that’s why you are content, because of the way things are.