when someone is indulging in a huge slice of pizza right in front of you, and the smell is unbearable, but you don't eat it. You think to yourself...in the end I am stronger and healthier for it!

When you're out fairly late at night (i.e. tired = low willpower) with family at a Mexican restaurant that you've never had before; chips and salsa are at the table, lots of food is ordered, and it all looks and smells really good - but you know you're really not hungry and already ate dinner several hours ago, so you repeatedly turn down every offer of food or non-water drink (despite your mother insisting that she wants to buy you something).

Feeding your little sister her more-than-she-will-eat serving of french fries but not taking/eating any of them (and wiping the grease and salt off your fingers rather than licking it.)