I am a big fan of hiking, so finding a place to practice it so close to the city was something extraordinary for me. Griffith Park is an excellent place for fresh air and outdoor activities. Although the Griffith Observatory is sometimes closed, you can always hike.
I recommend climbing as high as you can and having a picnic there while enjoying the fantastic aerial view of downtown LA. If you like taking pictures, the highest area of Griffith Park gives you a beautiful view that will allow you to take photos worthy of showing them to all your friends. The jackpot is watching the sunset. See how the sun sets, the afternoon gives way to night, and the city's lights become the perfect contrast of the sky with the stars... It is simply magnificent! If you are in Los Angeles, you should definitely go to Griffith Park and see everything from above!