"Better to stop short than fill to the brim. Over sharpen the edge and the blade will soon blunt... Retire when work is done. This is the way of Heaven."Know when to quit. Respect your limits. Understand when a workout stops being beneficial to you and end it there. No advice could be so simple and yet so ignored. One day as I was running around the lake, I had done about 5 of my planned 8 miles. The run felt really good. My heart rate was right where it should be, but there was a cold front coming in and the temperature had already dropped by about 20 degrees since I'd started running. To complete my workout I'd have to run by my car and come back to it. I opted to stop running while I still felt good and my clothing was still adequate. The additional 3 or 4 miles was not going to mean much fitness-wise if I wound up sick because of another 10 or 20 degree drop in temperature that could have occurred in the interim.
This advice is especially relevant if I am contemplating a speed phase. Before I might have a 6 week block of speed work scheduled and I might try to extend it to 8 weeks to see if I could eek out more from myself. In retrospect, not understanding and respecting this one insight is probably the reason for each and every injury I have ever had. Now I'm satisfied to complete 5 good weeks and wrap things up. Sometimes, especially in triathlon, less has to be more.