1 month out, your goal is to recover as much as possible from every workout. It's very easy to put in random "confidence building" long or intense workouts but often times, more damage can be done if you are trying to "prove" something with your body in the last few weeks before a race. Fitness is gained over time and to race strong, you have to periodize your training so that you can build, peak and taper appropriately.
Physiologically and psychologically, athletes need rest days!
Bottom line, you can train as hard as you want during a workout but resting your body creates better balance between your life, family, work and fitness goals.
Here are some subjective measures (in addition to blood work) measures that may tell you that you need to take action now and rest your body. If you tend to find yourself injured, burnt out or overtrained throughout or at the end of a training cycle, it's recommended to work with a professional who can help you create a plan that puts the appropriate amount of training stress on the body so that you can recover and train harder the next day:
Keep in mind that it requires a long term relationship with a coach and good communication between coach/athlete to develop the right plan to help you reach your season goals.
-greater RPE for a given effort, inability to hit previous paces/efforts
-unable to perform consistently
-chronic aches in muscles/joints
-loss of enthusiasm for the sport ("I don't want to do this anymore, I don't care about my goals")
-injuries popping up (or ones that won't heal)
-decrease immunity (increased colds, sickness, headaches, etc.)