Talk about happy landings... :D

Anyway, the simplest way to help the OP is probably if someone knows a good gym with sauna and showers (but without the club) in Dusseldorf where it's possible freshen up and maybe also have a work-out if deemed necessary? Any such place that sells day passes?

You may want to look here: http://www.duesseldorf-tourismus.de/...a/duesseldorf/

But beware, there are several "clubs" among common search results, like the one Google puts on top of the list when searching for "sauna düsseldorf". Now this would be the club, so be careful: http://www.phoenixsaunen.de/duesseldorf/.