Traffic

Instead of driving to work and/or school and back every day, consider taking your local mass transit bus. This ride can save you time and money.
Even if the ride is not the most direct and you are in traffic longer than if you drove, consider yourself gaining time since you have that extra time to work on something else instead of paying attention to the road. Read a book (or get a little farther on that novel you've been workin' on... y'know… with the compelling protagonist?) This will be far less stressful than fighting traffic and can give you that little needed relaxing break during the day.
Often you can get special passes that are good for so long and only cost a set amount. These are also usually cheaper for students and seniors. (For those with children in middle/high school- if you're a certain distance away from the school, sometimes it is free for your children to take the bus to school.) Add up how much it would cost you to ride for a month as opposed to how much the gas would cost for that month and the wear and tear created on your car. Chances are, you could save a significant amount of money.
By riding mass transportation, you are one less car on the road, which helps traffic and the environment. Some city busses have even implemented environmentally friendly tactics, such as running on forms of biodiesel.
For an added plus, try riding a bike (when feasible) to places instead of driving. This is even better for the environment than any vehicle and gives you some good exercise!