Mostly what the others have said. Cycling is a fitness/weight loss thing for me and I know how likely it is that If I chose another option I'd just keep dong that until all the good work was undone. Plus it's how I get to work so while I could drive, and will be doing so tomorrow as it's the Christmas do, I've got in to the mindset that I cycle to work and I'm happy thinking that way. A few journeys have been real chores of late, but there tends to be at least one positive with every trip.
When I do drive. I spend ages just stuck in traffic thinking how much quicker it would be on the cycle.