I find that the busier life gets, the less interest in sex and affection I get.
There's a couple sayings that come to mind:
"Act as if"
"Fake it until you make it"
I have found myself that when I "make" myself "act" loving and caring and affectionate and sexual, my mind and my body follow along.
I dare you to try this:
When you're in a bad mood - cranky, moody or whatever - jump up and yell "TA DA!!!"
If you can do that and STAY in a bad mood, there's something seriously wrong with you.
Chances are - if you do that - put all your effort in it - your body and mind will follow.
Smile when you're moody.
Touch your partner gently when you want to punch someone.
Touch your partner in loving, sexual ways with the express purpose of enhancing THEIR pleasure - and watch your body and mind follow into that mindset.
Fake it until you make it can change how you feel.