I'm not very good at drawing ponies running, so I decided to try this prompt from a different angle. In this case, Tough Cookie, being a pony of both a powerful appetite and strong spirit, has participated in (and even dominated) her fair share of eating contests. She's always looking to improve, however, and so, every once in a while, she pays a trip to Donut Joe's to try and break her previous records. Syntax always accompanies her to time her, for even though he often banters with her about her weight, he's willing to support his close friend in something she enjoys. Plus, Joe makes quite a lot of bits from Cookie's donut binging, so it's a win-win for everypony. =P
I'm also not good at drawing details backgrounds, hence the simple-colored ones I've employed throughout the Training Grounds, but I did my best to recreate the interior of Donut Joe's donut shop.