Until this summer I only cycled occasionally, but since I stopped driving in June due to dizzy spells, I was sort of forced in to depending on the bike as my main mode of transport.
Since that time I have built my mileage (1600 to date), stamina and fitness up and now have a totally different outlook to cycling.
I have turned down offers of lifts to work, preferring to stay on the bike and even though I'm expecting to be driving again early in the new year, I'm fully intending staying on the bike.
So, although I started back on the bike for none of the options in the poll; and there are both financial and eco aspects to riding, my main reason for staying in the saddle is fitness.