Sun Valley and the greater Los Angeles area have a mild climate which means you will typically not have to battle blazing heat or freezing cold while trying to walk your pup. Additionally, as Sun Valley is located at the base of the Verdugo Mountains, it is subject to flash flooding, but most of LA's rainfall happens during the winter months.
Since Sun Valley is at the foothills of the Verdugo Mountains, it is quite hilly throughout the neighborhood. Some residential areas are flatter, while the south and southeast areas are closer to the mountain range and, thus, have more hills. Sun Valley is also largely artificial terrain with all the residential and commercial buildings and neighborhoods. Thankfully, Sun Valley is surrounded by plenty of natural terrain with several mountain ranges nearby so you likely will not feel too trapped by the greater LA urban environment.The boundaries of Sun Valley are not linear, but it is bordered by the following other neighborhoods: Hansen Hills, Stonehurst, and Shadow Hills to the north, Sunland-Tujunga, Verdugo Mountain Park, and La Tuna Canyon Park to the east, North Hollywood and Valley Glen to the south, and Panorama City to the west. Both the Golden State Freeway and the Hollywood Freeway run through Sun Valley and should be avoided by pedestrians.
Other local greenways include Sheldon Arleta Park, Strathern Park North, Jamie Beth Slaven Park, Strathern Park West, and De Garmo Park. Depending on the size and location, some of these parks have more general recreation areas while others have some nice paved paths to walk on.
If you and your pup are looking for a little more adventure on your walk, La Tuna Canyon Park and Verdugo Mountain Park have several miles of hiking trails and are located immediately west of the neighborhood.