Today during my track workout, I blew up after about one set and had to take a break and start over. Even after a 5 minute break, I still blew up after a set; each rep I ran was slower than the last. I'm almost certain it was related to the sudden rise in temperature and my hydration. In any case, what do you guys usually do in these types of cases? Scrap the workout and do an easy run? Try to do the workout later in the day (an extra meal and hydration might help)? Or just skip running altogether that day and continue on with my week?