It has to become something you do routinely without having to make choice. The more decisions you need to make, even about trivial things, the more opportunity you have to find a reason to not ride. I've also found it helpful to take motivation out of the equation, because waiting to want to do something often means it won't get done. If you don't frame it as a choice then it's easier to push through reluctance and just do it.

I found that preparing everything I needed the night before work helped a lot. Everything I was taking to work was on the bike and whatever I was going to wear was already laid out when I got up in the morning. Since everything was ready I didn't have to stop to decide about what to wear, gather up everything I need to take to work, find my keys, etc. I also kept a spare change of clothes at work.

Plus, traffic is really aggravating where I live. My bike commute took me 20-25 minutes. Driving could take anywhere from 10-60 minutes, not including trying to find a parking space. The bus was about 30-45 minutes. On many a morning when I really didn't want to ride my bike I reminded myself of the numbers. If it was raining, I reminded myself that I would be spending about as much time walking in the rain and waiting for the bus as I would riding my bike home.

If you don't ride every day, it might be helpful to plan out which days you'll be riding in advance. That way, you don't have to decide if you want to ride in the morning. If it's Tuesday, it's bike day.

The key is to set yourself up on a predetermined path that you can run on autopilot.