A good rule of thumb is that below 20 miles a week you should not increase your weekly mileage by more than 2 miles a week; above 20 miles a week, you should not increase your weekly mileage by more than 10% a week.
At 230 calorie per cup of cooked lentils, lentils fall in the same range as cooked brown rice, potatoes and bananas. Some fats like butter, oils, nuts and meat are higher in calories, while non-starchy vegetables contain fewer calories per serving.
Lentils are a good source of protein and fiber, but the quantities vary with the variety. A quick check of the nutrition data on some labels shows that green lentils are particularly high in protein (13.5 grams per cooked portion), while the black type score well in fiber (6.3 grams per cooked portion).