Doing 30 miles per day on a road cycle...?

The time it takes to do a certain distance can vary a great deal depending on conditions. Headwinds can slow you down, and there may be more climbing in one direction than the other. You may be eating plenty, but when you eat is as important as how much you eat. One way to help avoid fatigue is to make sure to eat something as soon as possible after your ride. For years I used to ride a similar distance twice daily, 5 days a week, and I found myself getting tired by the 4th day every week. Once I learned the trick of eating at the right time, I could ride much more without getting tired. Another trick: don't focus on speed, do half of your rides at a relaxed pace, don't try to go all out all the time.