"One of the most basic tenets of training is a hard one to sell to ambitious, impatient runners. It's that you must run less than your best most of the time. You just can't go all out, all the time."

Sometimes it's hard to know how hard your heart and lungs are working when it's late afternoon. After a particularly wound-up work day. I dunno about you, but I want to run hard. Work out those mental kinks. It wakes me up and relaxes me all at the same time. So, if you want to keep running, do it right. Or, limp around at work, all wound up.