This is not a resolution--it's barely a thought

I once had a doctor tell me to walk one hour a day--no gym, no diet. I could not think of a good reason why not, so I did--for years. I did not lose an ounce but I guess it did me no harm--EXCEPT I now have painful knees and don't want some medical jackpot to maybe (or maybe not) fix them.

 Sooo...I cannot walk to the mailbox, much less for an hour.  

But I keep reading that exercise is good for arthritis--which I assume I have. But doesn't arthritis come from repeat stress on joints?  

I am thinking of at least entering a gym and asking some trainer.  

Me, a gym.  

I get it free under my health plan. Silver Sneakers or some such chirpy name.   What do you think?