Mind games

A study has just been published giving scientific proof that the last piece of chocolate does taste better than any other pieces before it, and that the theory can be applied to other situations: "It's something motivational. People may want to get something good out of the final piece while they still can or they may have a general expectation that things end well, which could bleed over into these insignificant or unrelated judgements."
I've always wondered about this - nothing seems so bad when you know it's about to end. Whether it's a disastrous holiday, a crap job or a challenging house-share - as soon as you know something is coming to an end, you start to think it was never that bad. What other simple explanations are there for how our brains work, I wonder?
I've noticed recently that, for someone who's always hated her hometown, I miss it a lot, and can't wait to go back and visit. I know, however, that it's really just a simple case of the grass always being greener.
 I'm very aware when these clichés take place - only wanting something once it's gone, only being nasty because I'm jealous...I constantly daydream about the past, but when I yearn for something I know I didn't enjoy at the time, I know it's a case of things looking better retrospectively. By just understanding why we behave certain ways and have certain thought patterns, though, does it make it easier to change them?
I know I'm scared of spiders because I've always had to watch my mother scream the house down every time she saw one, and I hate confrontation because I was bullied at school. I understand a lot of the reasons behind my flawed perspectives and irrational fears.
But understanding isn't really enough to stop these patterned reactions from happening. There are thousands of studies into human behaviour - but being aware of  the reasons why we behave the way we do doesn't always give us the power to overcome them. 
Now I understand why the last Malteaser tastes so damn good, though - will it make any difference? It just might. I now know to trick my brain into thinking that every piece of chocolate is the last piece. Perhaps there are some reasons behind science, after all.