They may forget what you said and did, but they won't forget how you made them feel.
The quote above, attributed to renowned poet, Maya Angelou is one I've seen multiple times. It's a very good reminder to writers to write with emotion. Sounds good but how hard, or how easy, is it?
It begins with us. I think writers need to feel the emotion within before they can expect to reach readers and make them feel it, as well. If we write about a trauma in our life, and all we do is report it by stating the facts, the reader may feel a bit bad but they aren't going to have that lump in the throat, or tear in the eye, or pang in the heart that they might if the writer unleashes the emotion in him/herself.
Sometimes, we writers build a wall around our emotional self, lock the gate and throw away the key. Or we tie ourself with the ropes of tell it but don't you dare feel it. Why? When we write with deep emotion, it can hurt. We've already been hurt so why would we want to do that all over again? Consider that reliving a traumatic situation can be a step in the healing process. No miracles, just a step. Crying can be a release and so can writing about a dark part of life.
Humor is not easy to write and make the reader giggle or smirk or smile broadly. Write it with the gleeful emotion you feel yourself and your reader will respond accordingly. How about fear? We may need to have experienced fear in some time of our life to be able to write with the true emotion. Think about how your body responded--heart racing, sweat on your brow, or unstoppable trembling.
One part of writing with emotion is to show rather than tell. If you tell what happened, it's a report. Show it if you want your reader to feel it. So simple but so important!
I read an essay that was subbed in my online writing group the other day. By the time, I got halfway through, emotion rose in me and kept going til the end of the piece. The writer did a wonderful job in relaying her own feelings to me, the reader. And she did it without being sappy. Writing with too much emotion is just as bad as writing with none. There's a fine line between the two.
There are whole books written on this topic. Google to find them so you can read about this topic in more depth.