Now I'm not sure if it is a bad idea or not, sesamin seems like a fairly safe idea and in the grand schema of pet owner practises this rates far below most bad things.
People compete their dogs in competitions all the time. Pulling comps interests me, if I were going to have my dog compete it would train and eat similar to me.
With that in mind exercising your cat would be a difficult task, diet not so hard. Since many frown on the idea of supplement use on your pets due to ethical reasons I've come up with an exercise and diet regimen all in one. I've assumed your cat over eats, and is lazy.
Conditioned taste aversion will be used - simple add a small dose of a chemical that will make your cat temporarily ill and throw up to your cats food, it won't eat your food anymore. Don't worry it is safe, farmers use this all the time for coyote problems just adjust the dose.
Put cat outside - it now must hunt for its food, you may have to help it out a bit, go to pet store and buy some mice so it gets the taste for them
Leave plenty of water outside - remember neglect is even worst then supplementing your cat with Sesamin
Unfortunately, your cat is now a lean mean killing machine. Who said basic psychology wouldn't come in handy? (I'm kidding, but it would probably work)