Never Too Old to Start Hiking: A 40-Year-Old's Guide

Question
How old is too old to start? I'm a 40 year old out of shape desk
jockey, but in 5 years I'd like to climb in the Sierras. Thanks.

Answer
I think anyone would tell you that you're never too old to start.  I would suggest that you do though begin slow and as you become accustomed to the various techniques and as your body develops, then you can begin to push yourself.  I think your goal is very attainable.  I think the better question is how hard are you willing to work?