I went to Boston for Red Hat Summit last week and it amazed me just how exhausted I was after all the walking to/from the train stations and around the convention. I used to bike every day to/from work when I was just a couple years younger and never felt as sore and tired as I did every day during the event. I really need to start getting out more, even just walking to the coffee shop 1/4 mile away on occasion and working from there.