I will discus progress made over the past couple of years in understanding the origin of the universal NFW density profile, and how the scaling relations between its relevant parameters can be inferred for dark matter halos knowing only trivial aspects of their assembly histories. Focusing separately on cold dark matter halos, I will emphasize the impact of transient dynamical states on their structural properties and show that, once these are accounted for, a single parameter is sufficient to predict concentrations for halos of any mass and at redshift. I will further highlight the role of diffuse accretion in warm dark matter models and its role in establishing the mass profiles of dark matter halos forming near the free-streaming scale.