Finding a place to workout East of the River can be a challenge. Whereas in NW DC you can't toss a chai latte without hitting a yoga studio, exclusive gym or a Washington Sports Club, finding a "gym" in southeast is just as much effort as actually working out. After living in SE for 5 years, I have learned to be creative and take it to the streets.
The Anacostia Park is among my favorite places for yoga stretches against the sunset cascading off of the river. Aside from the gangsta geese that take over the roadways, there are soccer players who pile in from Virginia to kick it around on the fields. On the weekends, I always see lots of beautiful brown families riding bikes, on roller blades, or even a few people walking their dogs.
This place is perfect for meditation. It is a catholic church with an onsite cop and the most amazing view of the city. I have done many meditations at this Peak off of Pomeroy.
Since moving to Pennsylvania Avenue SE, I have fallen in love with Fort Dupont Park. Though small and the trails are little rugged, this park has a beautiful path that circles into NE and through some cute green neighborhoods. During the summer, I cycle through the park and always think of crashing someone's cook out.