Not been in many years, but spent a large part of my childhood watching people row and sail back and forth. It freezes over in winter and in February 1893, Jack Selby drove a coach and four horses across the reservoir.
Need some clean air or just a time-out? Kew Gardens is a short train ride away from the city centre but is provides you with space, greenery and and a small holiday for the lungs. The garden contain tropical glasshouses and interesting architecture, so it is a treat for both body and mind.
London’s wildest and best park to get lost in. Just follow your instinct, chase trees, go up to the viewing points and you’ll always find breathing and mindspace in Hampstead Heath. If you can, visit often, as it goes through wonderful changes over the seasons.