Similarly to Calabi-Yau 3-folds in dimension 6, G2 manifolds are certain 7-dimensional manifolds that appear in the Berger list of possible Riemannian holonomy groups; they are Ricci-flat and admit special 3-dimensional stable minimal submanifolds, which are called associative submanifolds. In this talk, I will explain how to construct and understand the properties of associatives in the cohomogeneity one G2 manifolds recently constructed by Foscolo-Haskins-Nordström.