However, I always congratulated myself (outloud, by name) when giving myself the treat, and pretty soon, the congratulating myself was conditioned as a reward for the activity, letting me drop (most of) the usage of actual treats.
Just treat yourself like a particularly stubborn and clever dog/cat/animal you're trying to train -- if marketing has taught us anything, it's that cheap psychology tricks work.
Honestly, you could probably just start with the secondary reward of congratulating yourself -- it's just important that you do it out loud and call yourself by name (eg, "John, you did a good job of running today"), so you hear it happening, instead of it being part of your mental dialog.
Generally though, I find that speaking to myself is psychologically different than talking to myself internally, so YMMV if that's not true for you.