The word of God will have little effect on its listeners when the lector proclaims it with no emotion.
Douglas Leal in his training manual, Stop Reading and Start Proclaiming, notes, "To simply read the words, even to read them well, and ignore the life that is within those words is to be unfaithful to the office of lector or Gospel proclaimer."
A little tough to swallow, perhaps. But when we don't study and know the stories, the settings, the characters and author's emotions in our reading, how much life can we really breathe into them?
Think of the emotions we unleash when we tell friends our great life stories: "Wow! I gasped in awe when I saw my wife holding our first-born child in that recovery room," or "When I heard the sound of those two trucks colliding head-on, I shivered in fright."
And so it goes in our proclamations. When we've internalized the text enough, we can then excite, warn, reprove, console or calm with the emotions and intent of the author and truly give our assembly "a word that will rouse them" as it's said in Isaiah 50:4.
In Mark 4:21-22a, Jesus asks, "Is a lamp brought in to be placed under a bushel basket or under a bed, and not to be placed on a lampstand? For there is nothing hidden except to be made visible."
The ambo is that lamp stand from where our hidden emotions can be made visible, provided we don't push them too far or be too dramatic. We must respect and be able to interpret the text true to our own emotions and not overly play-act the author and characters.
The makeup of the assembly might also suggest how much or little emotion we inject. Different Masses often have their own communities with different emotional norms and expectations. We may "kick it up" a little more at a life-teen Mass than at an early morning service attended largely by the elderly.
Just try to convey the right dose for each different audience as best as you can assess it, without being a chameleon proclaimer.