The White Clay Creek State Park in Newark, Delaware is one of the most popular parks in the state for trail running and hiking. The nice thing about White Clay Creek is that it has a huge variety of landscapes, from gently creeks to thick woods and rolling hills. If you want to clear your head and de-stress, strap on your running shoes and hit the trails! There are 10 or so official trails and 2 or 3 are specially designed for trail running.
The park is closer to town than many other ones so the easy areas can get a bit crowded on weekends. Hit one of the longer loop trails, though, and you'll find yourself smack dab in the middle of a pristine Delaware maple and hardwood forest without a soul in sight. That's actually my favorite part about White Clay Creek State Park: you can really, really connect with nature without crowds and without noise. It's perfect.
There's also a lake where you can go boating and fishing and a historic estate on the property. The estate is mainly used for things like weddings and events but if you're interested you can call ahead and book a tour.