This is a women we're talking about...
As soon as she got on that treadmill, she was sizing up how many miles you've ran and calculating your minutes-per-mile based on how long you've been running. This is some tricky shit. You have to make sure even if your wiped out at this point, you bump your treadmill up to speed level 9 make sure you run until she's finished also. Casually turn your head toward her and give her a casual smirk 'whats up?', casually.
Also, try not to sweat too much, because sweating too much is disgusting but sweating a little bit may turn them on from pheromone excretion. If you're not boning in the locker room 15 minutes later, then ever porno I've seen is a lie.