Sort of similar to the personality swap/identity changes that atcpony has done, this is something that I commissioned in a similar vein.

Fluttershy found some curious-looking weights in her house one day. She wasn't sure where they came from, but after lifting them for a bit, she started feeling good and seeing some almost instant results. Surely, something like this was impossible, right?

After a bit, Fluttershy didn't care, just focusing on building those gains and looking good. Who cared about losing their dainty, curvy form or their marehood? All that mattered was pumping those dumbbells and getting that swolle look, bro!

Butterscotch was ultimately very satisifed with the results. He knew he was going to be hitting the gym a lot more often now, maybe put in a lot of new workout equipment around his place and the animal sanctuary. A big stallion like him needed to keep looking beefy after all.

In fact, maybe he should do a few more sets and go for a run? He hadn't worked nearly enough of a sweat up.