I live in London. Taking out the trash is more of a mental than a physical challenge because our rules on recycling are so complicated. By the time I have sorted out my different grades of plastics I wish that I hadn't.
I have tried running in the park, sprinting on the track, playing new people. I still really enjoy tennis. But it is the mental focus that I need to train properly that has deserted me.
I agree about pick up games of soccer or other sports because the competition is its own stimulant. But winter is here, the days are short, and I am at work during the hours of daylight...
Kite boarding sounds fun. I did something similar with skiing a few years ago.
Short intense periods of activity may be the way forward.