sleepygeek - Try body-weight exercises. They are great for toning and building muscle (though women tone more than build, rather than men who build rather than tone).
I'm sure you can pull it off well.
Powerline!Max - A Goofy Movie (Otakon 2015, completed)
Possible Future Cosplays
Ippo (Hajime no Ippo)
Teen Goku (Dragonball/ Dragonball Z)
Steve Rogers civilian uniform (Captain America: First Avenger)
My Facebook cosplay group - Southern Maryland Cosplay
(Anyone can join)
Author of the "Getting Fit for Cosplay" Katsucon panel.