Start with 4 small, sealable containers (mason jars work great). To each container add 1/4 cup of oats, 1/4 cup of yogurt, syrup, a pinch of sea salt and 2 tablespoons of chopped walnuts; mix well.
Dice peaches. Reserve half and divide remaining peaches between containers. Cover and refrigerate overnight.
Before serving, top with reserved peaches and more chopped walnuts.