Parque Estatal Sierra Morelos is Toluca's easiest escape into open hills, with paths, picnic areas, and viewpoints over the city and the surrounding valley. It is not wilderness, but it gives you fresh air and altitude without the commitment of a Nevado de Toluca excursion.
The park is best in clear weather, when the views justify the climb and the trails are dry. Bring water and sun protection, and avoid treating it as an after-dark shortcut; it works as a daytime local recreation area, not a polished tourist complex.