I have been using a mountain bike for my daily work commuter for the past 2 yr.'s and lost 60 lbs.. I recently purchased an Orbea Aqua for longer rides and I am pretty happy with it.
I will turn 50 this year and going thru mid-life crises. One of my fitness goals is to complete a century ride (not win, just finish). Today I rode 36 miles, so I have a ways to go. I really enjoy cycling but have been away from it for to many years.