When we try to deny ourselves what it is we fancy at that precise moment, we are suddenly overcome with desire to go against and be devilish. Let's show this by analogy of religion. My body will be the temple, "I" will be the devoted follower and some lemon ice cream will be the act of prayer.
Now, the temple is waiting for you to arrive and pray. It's what it wants. The devoted follower is a little bit angsty about the fact that she has just got back from holiday and done waaaaay too much prayer (and coincidentally has put on about fifty prayer mats worth of tummy love). But the temple is adamant that the devoted follower must come to take part in prayer. So, because of the whole "my body is my temple" thing, the devoted follower has found temptation (by way of a bowl and spoon - with her name engraved on them) and gives in. The temple is happy. The act of prayer is finished and therefore not wasted. In spite of the initial begrudging attitude shown by the devoted follower they feel better for it.
Why? Because doing what you want for you turns out not to be such a bad thing after all. Though this rule may not always apply - do not indulge in mass acts of prayer before bikini shopping. Unless this is actual prayer to find one that fits/doesn't depress said shopper/isn't really expensive for a piece of fabric that is essentially just going to cover your behind in water. Right. More blooming prayer for the temple! Coincidentally, Croatian lemon or kiwi ice cream is fantastic.