Why do i feel embarred when I go out running?

Alright so theres a park near my house. Its actually a huge botanical garden so not really crowded and the perimeter of the park is the perfect place to run (around the park) since the sidewalks are wide and usually empty. Problem is...I dont know WHY but I feel all embarred when I go out running. I am not overweight. I am 21 years old, lean, in great shape and yet I feel weird. It just feels as if Im out of place and everyones looking at me.