This is just another way of saying don't be an emotional based decision maker, don't be impulsive, or think about what you are doing / not doing. For me, phrasing it this way simply invites engaging about what it means to not allow a transitory feeling or emotion to rule on my actions.

I start to introduce the power of feedback mechanisms and discipline. When we give in to mood we have an often temporary high followed with a low of sorts. [ It doesn't always have to be the pleasure & guilt dynamic. ] What happens is the decision to arrive at the immediate high receives the connection to a response from mood and the further down the road low just gets labeled as a new mood that needs to be placated. The opposite is true where discipline to do an uncomfortable thing now yields a down the road high where if we can remember to associate that feeling of high as a reward to the decision to deny comfort (in this example) we can modify behavior and decisions.