Heat + Humidity = Wall

[OakLeaf]

I guess to address your second question, how to handle it when you feel like you can't ...

#1, be safe. If you're overheated, get your core temperature down as fast as you can. Drinking crushed ice will cool you faster than iced beverages, since you're actually swallowing the ice. Immersion in an ice filled tub if you have access to one, or cold towels all over, or hosing yourself down. If it's not quite to that point, either stop in a shaded spot, or if you're on flat ground without a headwind, sometimes very slow gentle pedaling is actually cooler since you maintain air flow that way without generating more body heat.

#2, which is what you did, if you're riding a loop you have no choice but to keep going until you're back where you started! Might not be pretty, but you have to keep going.

#3, accountability. During my marathon training, pretty much every interval workout my coach gave me, I'd look at and be sure I wouldn't be able to do it. Every interval, I'd be sure I couldn't do the next one. Most of the workouts, I did just fine. I knew my coach would see my track and didn't figure there was a point in paying him if I wasn't going to attempt to finish the workouts. You don't need to hire a coach, you can train with a partner or, if you're somewhat motivated but want a little extra oomph, just follow a free training plan. Just, beware of accountability without very specific goals, because that way lies burnout.

Never forget to have fun!!



ETA - adding one thing on hydration, several people have mentioned very frequent drinking. I've read that if you just sip, your stomach isn't stimulated to empty as fast, and you'll actually hydrate yourself better if you drink larger amounts less frequently.