In the scene you're about to do, what just happened the "moment before"?
Something ALWAYS happened just before this. Sometimes the script will give you clues, sometimes it's totally up to you.
We could easily make a list of what it could be when it's up to us...
You could have...
...just had a fight.
...just woken up.
...just stepped in dog shit.
...just got laid.
...just had your dog die.
...just got a new job.
...just quit your job.
...just won a $5,000 scratch ticket.
You get the idea.
Go make your own list. At least 10 items. Pic two for the sides today.
P.S. I find it's better to make a list that has nothing to do with the scene you're about to do. This way, you get to try some really random stuff, and have a little more outside-of-the-box fun.
Of course, if it's obvious what just happened, you should probably try on that choice too.