Susan, you have got to be having a laugh! Given the sort of work that inevitably end up doing on a daily basis, I have no need to 'exercise' while I work (lugging archive boxes, moving huge piles of files around, hole punching, photocopying, furniture reorganisation etc etc) and neither do I need to pay for a gym membership either!
Cannot see it would really work as (IMHO) it could distract from the work at hand (especially the more tender-minded, but still very intelligent male fee earners that I work for!)!
Just my take on it, although ... having said that, there are a few partners who I would pay to see fall off their treadmill if they got bad news or grief from a client!

Jess