Is action a form of discontent? I know Buddhism stresses the importance of being a content person, but I can't help thinking that any action such as walking or even shifting my foot is a form of dissatisfaction for current moment. Why would I change anything if I am content?
I would suggest that Buddhism does not promote the importance of being a contented person, especially by suppressing any feelings, perceptions or other parts of experience. Instead, by learning to know dissatisfaction (suffering, dukkha) very well, we notice that the discontentment is separate from the experience (i.e. pain is pain, sickness is sickness, it's our minds that adds dissatisfaction on top of that).

By practicing to recognize dissatisfaction, we can then learn to put that dissatisfaction aside, and simply experience each moment as it is (painful, pleasurable or neutral). Once we are able to put dissatisfaction aside, contentment naturally arises.

I would like to stress that Buddhism does not promote becoming a contented person - this holding on to "me as a person being contented" is also a cause for discontentment, since it is certain to change. Once the situation changes ("me" no longer being content), there's dissatisfaction - my view of myself being contented does not fit with the experience I am having.

Walking or shifting your foot is not inherently dissatisfactory. It is what it is, what you experience are the sensations of lifting the foot, changes in pressure on the footsole, and so on. The experience can be pleasurable, neutral or unpleasant, but that does not have to equal dissatisfaction in that moment. Our minds add that on to it. Once we're able to let go of the added layer of judging the experience as satisfactory or unsatisfactory (it shouldn't be this way or this is great), contentment is with us, here and now.