Run around Lac Annecy (2018 Winter Olympic candidate). It was hot (35 degrees and I was stupidly running in the midday sun) but the saving grace was that there was a pancake flat cycle path to run on.
Tried out a Moneghetti interval session (2 x 90 (90), 4 x 60 (60), 4 x 30 (30), 4 x 15 (15)). The path had 500m markers and I was hitting 15 min 5k pace for the minute efforts (think I should have been slightly faster but will let myself off). Good session with lots of bang for your 20 minute buck.