Read about hyperbolic discounting, if you haven't already.
Assuming a conflict between short- and long-term decisions, the general advice is to mentally bundle a given short-term decision with all similar decisions that will occur in the future. For example, you might think of an unhealthy snack tonight as "representing" the decision to eat an unhealthy snack every night.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.