Mason Park in Annandale has nice trails for hiking. Some people just circle the small pond for exercise. There are two loops back in the wooded area; one about 3/10 mile and one about 9/10 mile. There are two buildings with public restrooms, tennis courts, and an amphitheater with shows some nights. 

Thursday mornings are the days to hike in the summer if you love fresh produce. That's when the farmers market is there. It's so popular that market can be chaotic; you can go to the right and park by the tennis courts to avoid the traffic jam.