I do it because I like biking and it is healthy and keeps me fit and the weight down.

I too, live in Silicon Valley. I could bike 16 to work faster than driving to shuttle stop and taking the shuttle down crappy El Camino Real to work. Same for ride home if I rode during commute hours, but I generally rode home later.

I also started eating healthier. Cut out desserts and snacks. Smaller serving at lunch. Dinner is a sizeable salad and a side order of protein. NO FOOD AFTER DINNER! Cut out bread and pasta. Combine with exercise and weight loss will follow. You really have to remember that you aren't hungry. There's a difference between "I'm not full" and "I need to eat something".

It takes a while to build up to long rides every day. My commute is 22 miles each way, and I bike to work in the morning and take the train most of the way home and bike 5 miles from the train. I am doing it four times a week now; Wednesday is my non-ride day. Commuting by bike means I commute for 2.5 hours. Non-biking is 2 hours, with 2 miles of walking. So commuting by bike really makes effective use of my time if I need 9-10 hours of exercise per weeks.

Keep riding; I think you'll eventually get to the point where you don't find that you need motivation. Unless the weather sucks :-)