"The tennis wall is and should be your best friend," writes a contributor to Improve-your-tennis.com. The gentleman above was apparently taking that venerable website's advice to heart last week, as he took over a section of the Powell Street BART and Muni station to improve his game.

BART board member Nick Josefowitz captured that video of the man's workout, saying "I thought I'd seen all there was to see at a @SFBART station. Then I saw this guy play tennis at Powell."

Those of us who've taken SF transit for a while might have seen this guy a number of times, so before you comment on how this has been going on for ages, cut Josefowitz some slack — he's only lived here since 2012.

And the important thing, really, is that this tennis player isn't sleeping in Powell Station. Sleeping in the station could, after all, get him arrested.

But hitting a ball against the Powell Station wall? Not only will that keep you awake, but it is the "secret that will help you to improve your game drastically." Everybody wins.