What are the writer's father and grandfather doing in the park?

Read the text below than answer the questions!

    Hello. I’m Sarah. I and my family are in the park. Today is Sunday. Many people are gathering in the park. Some people are sitting on the grass. Some people are sitting on the bench. My brother is wearing a light blue-cap. He is walking our dog, Jerry. My dad and grandfather are wearing running shoes. They are jogging. My mum is wearing glasses. She is holding a carton of milk. She is reading a novel from Andrea Hirata on the grass. And there are my friends, too. They are taking their bike. They are biking around the park. Look at the big tree! There are a flock of birds. They are perching on the branch. The park is so crowded today!

What are the writer's father and grandfather doing in the park?