Several years ago (wait, let me figure it out... aaaannnd.... got it! Five years ago), I was in a Parent Education class with Big Girl (in our town we have these wonderful free classes offered by the community college) and our teacher imparted a certain piece of wisdom during discussion one day.
I think the topic was discipline or tantrums or something. All the children in the class were turning three during the school year, so it was something about the difficulties of living with a two- or three-year old.
She said, "try to say yes."
For me, this sentence was jarring. Say "yes" to my toddler? But she is always asking to do things or eat things that just aren't appropriate! My whole day is "no, you can't have candy right now, I'm making dinner," "no, we can't go to the zoo, we have to get groceries," "no, you can't climb on that statue, we're in a museum," you get the idea.
So, how about changing it to:
"yes, you can have a piece of candy after we eat a good dinner"
"yes, we can go to the zoo tomorrow (or Saturday...), what animals do you want to see there?"
"I see that you want to climb; where do you think we should go to do some climbing?"
It sounds a bit Stepford-Mommy, I know; but it has really helped me. It doesn't help all the time, but it does cut back on the tantrums. Plus, it helps me stop being so serious, which is a good thing for me. Sometimes I lose perspective and feel like altering my plans for the day would be the end of the world. It helps me to take a step back, and see the bigger picture.
These kids will not be little for long.