I have been having car trouble for about the past week or so and while this has been a little frustrating, not to mention expensive, it has also forced me in a little different direction. I still have places to go and live in a city where public transit is one of the best jokes ever told in that you will laugh at it until you cry. That has left me on a bike, the most popular mode of transportation of 10 year olds everywhere. However crazy this may be, I seriously had overestimated my cardio fitness when left to pedaling my way everywhere. By the way, even in the Midwest nothing is truly flat so even the slightest elevation can grate at you over a few miles. For cardio today, ride a bike for 10-15 miles or so. It sounds a lot more daunting than it is.