Self-care is an important part of training. All of the benefits of training are realized in the recovery. It is often said that there is no such thing as over-training, only under-recovering. How seriously are you taking your recovery?
Do you see a bodyworker or clinician about your aches and pains? Are you doing any mobility work? Are you sleeping well? Focusing on recovery is low-investment but high-yield.
On days like today, drink lots of water, move the body, and prioritize quality nutrition.