Seriously considered driving today because my legs were toast on yesterday's ride with the first real heat and humidity of the year. The high topped out at 90+ and I was really dragging, plus I stupidly went for a walk with my coworkers at 3 pm. Decided instead to take my faster, lighter bike with no lunch to cut down the weight this morning and that made a big difference. The wind was milder than usual and I was able to dress lightly due to the heat (70 F at 6 am). A dose of Vitamin I (ibuprofin) also helped.