When I need to take a short break or just refresh my brain quickly, I like going to Moczydełko Park (not to be confuse with Moczydło Park which is located in a totally different side of the city ;)). It’s a small park in the residential neighbourhood Kabaty located by the metro station of the same name (the first station on the first line of Warsaw’s metro).
In Moczydełko Park there is a small lake surrounded by lush greenery. Since I live nearby, I remember the times when it was a wild area and at night I could hear from home the frogs living by the lake. Although the place has been developed, it hasn’t lost its wild character. Apart from frogs, you can still meet e.g. ducks there.
It’s also a place that many parents choose to walk with their children, as part of the park is occupied by a modern playground.