Your body needs rest to become stronger. As endurance athletes we are always pushing our bodies to their limits. If we push ourselves and never allow for recovery, then the body is unable to adapt to the new workload and the hard work we put in becomes lost. I cannot stress the extreme importance of a recovery day or days within the week. This allows your body to recoup and repair so that it can get ready for another week of training.
But, what happens when you do not have a recovery day planned for another four days and your body is just beat? Do you “man up” and push through it? Do you back off of your intensity or cut your mileage short? Do you skip your workout altogether? What you do will depend on a number of factors, but let me encourage you to be willing to deviate from your planned training if your body is struggling.
Without training your body will struggle to make fitness gains. Most people know this. But, training in a constant under-recovered state can also hinder your fitness and performance gains. Learn to balance easy and hard days, learn to modify workouts when necessary, and you just might find yourself getting faster.