connect.garmin.com/modern/a...
It wasn't fast, it wasn't hot, it wasn't a high cadence - no idea why it felt so hard. Legs felt like concrete, breathing was fine but nothing seemed to click.
I tried to stay in the easy/aerobic zone but I ran out of steam towards the end of the run (checkout that decline on my cadence ;-)) and kept oscillating between aerobic and threshold so the 'time in zones' is a bit skewed.
Oh well - a 5K - I'll take it