General health and fitness. I lost around 3 stone a couple of years ago, from 17.5 stone to 14.5 (I wanted to do a parachute jump - highly recommended). I lost it through diet and walking. It's started to go back up again and I wanted to do something a little different for variety. A good friend has recently started an encouraged me.
My first ride was 2 miles (!) and my legs were shaking afterwards. Definitely different muscles from walking. I want to get up to 20 miles or so within the next couple of months.