Have to agree with thistimeisdifferent - variation is the key. Throw something new into the mix every few days or at least once a week. Tomorrow I'm roasting a whole trout - i've fried (frylight of course) fillets before, but never done a whole one (ok, bit of an extravagance, but much needed one after three days of instant mash/beans/quorn sausage). I've also (and it sounds odd being 36 to say this) recently introduced tomatoes into my food stuff (I thought i hated them - but recently found that maybe i didn't). If you're a red/green person, and always alternate between the two - mix it up - have a few red or green days in a row.
It's all too easy to get into a routine. I did SW about 7 yrs ago, and you could tell the day of the week by what i ate. Tuesday it was steak, wednesday fish, thursday chicken, (can't remember what friday and saturday was), sunday was bolognese and monday was the left over bolognese. It was that samey.
Sometimes my week day meals even now are samey - but i sometimes work odd hours (getting home at 9 or even 10pm (or later)) and when i get home want something that's quick, and easy and simple - no faff, no fuss - but come friday night, and it's what can i do that i haven't done before, or not in a few weeks.